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Thoughts on Changing Transmission Fluid
Decided to start a new thread on this topic. Have any of you guys ever changed the lifetime oil or ever thought about it?
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it should be done as regular maintenance no fluid is life time I don`t care what anyone says.
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This topic has been beaten to death. There are valid arguments on both sides...so use the "search" button above and draw your own decision/conclusion.
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I got my X5 with over 100K miles on it. The trans would slam in to gear when taking off from a rolling stop.
Had the trans filter and fluid changed and the torque converter flushed. Trans shifts like butter now. There is no such thing as a lifetime fluid or filter. Unless of course you want the life of your car to be shortened. |
Hey Brandon002 I have the same year and model as you. Did you change the oil yourself? At what mileage did you change the oil?
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I had a local german indy do mine. It was 419 including parts, labor and fluid. I figured it was worth it when parts and fluid alone were going to cost me 250 minimum.
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Having them do it got me a torque converter flush too, which i wouldnt have been able to do at home.
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146k miles.
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Lifetime .... of the gearbox..... but if you want it to last a lifetime of the car, you gotta change it
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Im not sure, but they guaranteed they changed all of it.
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Interesting. Mine has 80k miles and when I looked at the pan it states that fluid is lifetime. Also awhile back a BMW service adviser told me that they'll refill the transmission if it was low at 100k miles.
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Do you honestly believe any fluid in a car can be lifetime?
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Ok, bcause they (transmission shop) changed 16 liters on my 4.4 with torque convertor and cost associated (similar than yours) but with Wynn's oil ..versus a lot of folks here doing DIY with 5 or 6 liters ?? ...my tranny works very good since the changed at 70k miles....here is more from that thread : http://www.xoutpost.com/bmw-sav-foru...2-4-4i-21.html |
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So don't change the transmission fluid... because it won't cause a problem?
I'm sorry, but no fluid is going to last forever and regular changing of the fluid is going to prolong transmission life. This is a fact. It's called "preventative maintenance" for a reason. |
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1) Mechanical abuse; 2) Overheating; 3) Fluid contamination; 4) Electronic malfunction. Hydraulic fluid, which is the basis of ATF, essentially does not wear out. The additives can be damaged though by excess temperatures and contamination. The BMW units are for all practical purposes, "sealed", so contamination is not an issue unless new fluid is introduced, whether by using the wrong type or performing an incomplete flush. As to overheating, the fact the vehicle is rated to tow 5000-6000 pounds without additional modification is a testament to the cooling capacity of the transmission heat exchanger. (For peace of mind though, I'd probably add an additional cooler if I were towing on the highside regularly. 2002 X5 3.0 243,000 miles (no fluid changes) 2004 325i 108,00 miles |
By not servicing transmission youre rolling the dice. New fluid will always be better than old fluid.
Brake systems are hydraulic and for all intensive purposes sealed. They need service. A transmission is a mechanic component. Why would bmw put magnets in the trans pan if there was no worry of metal particals contaminating the fluid? Those metal particals need to be removed periodocally as they can clog passages or cause even more rapid wear on othe components. Its your own choice ultimately, but it is a gamble that can more than likely have the odds swung in your favor with preventative maintenance. |
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Preventative maintenance does not consist of changing out things just because. And transmission fluid doesn't wear out based on miles or km, it wears out based on incidences of overheating. Transmission fluid does get oxidized when it is overheated. But it never stops being slippery. And the lubrication demands on transmission fluid are very low, which is why a 10w hydraulic fluid provides sufficient lubrication. Yet most proponents of changing it talk about the mechanical wear that cleaner hydraulic fluid will somehow prevent. If the fluid was typically wearing out, considering all of its critical characteristics, across a sample of BMW vehicles, and leading to subsequent transmission failures, you would see a normal distribution (bell curve) representing transmission failures related to fluid degradation. We don't see that. And we see transmissions running hundreds of thousands of miles on original fluid without drama. Those are real data points. Changing fluid on a transmission that is working fine, and then pointing out that nothing bad happened, doesn't support doing preventative fluid changes. The failure modes we do see tend to involve sensors, wiring harnesses, and so on. There are lots of random nuisance issues. None of them appear to correlate very well to fluid degradation. If the fluid goes out of spec due to abuse or whatever, it is reasonable to change it. That appears to be what happened to your transmission. But if there are no shifting issues, particularly at higher mileages when there are likely to be deposits built up throughout the transmission, then the economics of regular fluid changes are very questionable. And the added risk of introducing a new, high detergent fluid into a closed system with varnish, etc, means that there is a risk of a transmission failure precipitated by the fluid change. It won't always happen, but it happens frequently enough to be recognized as a known failure mode, even with the correct fluid correctly installed. It all seems counterintuitive, because people want to do what is best for their vehicle. We used to change oil at 3000 miles, something not at all necessary on these vehicles. We used to do tune ups. We used to adjust valves. There are lots of maintenance activities that are no longer relevant. The thinking on preventative maintenance, and predictive maintenance, has evolved a lot in the past few decades. It is no longer intended to prevent failures. It is intended to produce the lowest overall operating and owning cost. And that means that fluid changes that cost money but don't produce an improvement are in fact a liability, not a benefit. And I told myself I wasn't going to wade into this particular topic again. Oh well. |
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What they have in common with transmissions is that they don't tolerate being overheated very well. Which is why race cars get new brake fluid very regularly. Shock absorbers are a better example, although others have dismissed that one here before. They are hydraulic systems, and sealed. We don't need to change the fluid in them. When they are worn out, we replace them. The fluid is lifetime. One could argue that changing the fluid would make the seals last longer, but we haven't considered that to be an economically viable proposition since the days of lever action shock absorbers on British sports cars. And there, it wasn't that the fluid wore out, but rather that the seals wore out, so the shocks were overhauled. |
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In 2006, and again in 2007, SAE published papers demonstrating that in fact used engine oil was better than new engine oil. The engine manufacturers know all this. Yet some still promote 3000 mile oil changes instead of 12,000 mile, which is demonstrably harming their engines. Quote:
I no longer have a membership or my copy of the paper, so the paper costs something to download, but the abstract demonstrates the point. The point isn't to promote the concept of lifetime engine oils, since engine oils are subject to contamination from the byproducts of combustion, and resulting decrease in TBN (unlike transmission fluid) But the papers do challenge the traditional thinking that new is always better than old. |
So then please exain how a simple fluid change solved my trans problems?
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Most likely the fluid was out of spec. That is when it is worth trying a fluid change, when you have a symptom like you had, as an alternative to just opening up the transmission. As I mentioned in post 20. But that is corrective maintenance, not preventative maintenance.
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So say the previous owner serviced the trans before any issue was apparent. Can you say for certain that the trans would have still had the same issue? Why not correct it before a prpblem occurs.
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Its a 400 dollar service done every 2-3 years. That small amount can save you thousands down the road in possobke trans repairs. There is no benefit in not changing trans fluid and plenty of benefits to changing it. New fluid is going to always provide better performance than old. Why not spend 400 every few years to help avoid thousands in repair bills. Why is there a filter in the trans? Do you not think the filter collects debris and contaminants?
I guess to each his own. I personally would rather roll the dice after stacking the odds in my favor. |
There doesn't appear to have been a downside to you changing the fluid. You restored the original functioning. What would have been the benefit to changing it in advance, on the off chance that it would have needed changing? You don't appear to have suffered any consequential damage.
The benefit in not changing the fluid is in not paying $400 every two years for something that doesn't appear to have any real impact on transmission life. The transmission has an adaptation process to deal with varying fluid viscosities. It isn't wearing out mechanically. Why would new fluid be better, unless the old fluid was overheated and had broken down? Especially considering the data above, about how older engine oil lubricated better than new engine oil in controlled tests. New fluid is not always better. Sure, the filter collects wear material. Not contaminants, the system is sealed. The only things in there are what was installed originally. The filter does precisely what it was designed to do, separate out and hold those wear materials, consisting primarily of friction material. The issue we are debating is whether changing the fluid actually stacks the odds or not. Do you have any data that shows that transmissions with fluid changes last longer on average? Or that transmission failure modes on these models correlate with fluid breakdown? How do you calculate these odds? |
Why not change the fluid at regular intervals to keep the fluid within spec?
So how long does a filter "hold wear materials" before the filter needs to be replaced? How long to the magnets accumulate metal particles before they need to be cleaned off? You mean to tell me that a filter that collects wear items will perform as well as a new filter for the entire life of the transmission? A new filter is going to perform better than an old filter. I saw my old filter after they removed it and it looked disgusting. So maybe the fluid will last forever, but the filter needs to be changed and that requires replacement of the fluid. And stop posting excerpts from an article on engine oil, you said it yourself, engine oil and transmission fluid are two entirely different animals. You go right ahead and believe the "lifetime" claim on the transmission fluid/filter etc... I'll continue to change mine at intervals as it gives me piece of mind and COULD possibly save me major repair bills down the line. |
Because you don't know that it is out of spec. With normal use, it won't go out of spec.
Filter is designed to last the life of the transmission. Magnets do not need to be cleaned off. If there is stuff stuck to them, great. That is what they are designed for, and where that stuff is supposed to be. Out of harm's way. Do you think it was your fluid that was out of spec, or that your filter was partially plugged? Which problem did you fix? If the filter was so bad, you could have replaced it and put the same fluid back in. I agree that it is hard for people to bring themselves to do that, once they are already in there. So you are saying that maybe the fluid will last forever? That is quite a shift in thinking. Yes, changing the fluid could possibly save you money down the line. But we have nothing to base that hope on, except "because it seems right". On the other hand, we know it will cost you $400 every two years or so. |
If youre against spending hundreds on maintenance every few years youre driving the wrong car. Like i said, you continue to run lifetime fluid and i will continue to service mine at intervals. I have always done this with all of my cars and i have never had a transmission problem.
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The oft-claimed reason for changing transmission fluid is because of improved lubricity, ie it will prevent wear. Taking all those particles out. Improving sliding and rolling friction between moving parts. In that sense, the engine oil article is completely applicable. Agree that it doesn't cover the subject of the additive package in the transmission fluid, and the friction modifiers. |
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I've never had an automatic transmission problem either, since the restoration of a 66 Mustang that had a failed Cruisomatic transmission when I bought it. No problems after overhauling it. I am not trying to talk you out of changing your transmission fluid. Each owner should do what they feel is right. All I was pointing out is that many of the reasons given for doing regular preventative maintenance fluid changes on X5 automatic transmissions don't hold up to scrutiny. They don't have an economic basis. But not everything we do has to have a payback. Sometimes it just feels right. |
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As mentioned, there are two strong camps on both sides of this issue. It is always an interesting debate. I am on the side to change the transmission fluid every 50,000 miles. I don't believe it is possible to have a valid study on either side of the coin that determines which side to join. There are too many variables. I don't know how to include a bell cure endorsing anything unless there is a subset of that curve for those that change the fluid. I can't consider the SAE study as endorsing your position either as I don't know what oil(s) they are talking about and moreover I agree with you--engine oil and transmission fluid are not an apple to apples comparison. As a sidebar I don't know about you but I changed engine oil a lot more frequently than I changed brake fluid on anything I raced and far far before 3,000 miles. Since this issue is no more than a debate I am sure you can discount this logic----there wouldn't be a filter in the transmission unless there is a reason it should be there. If changing the fluid releases stuff that will harm the transmission, if I change the fluid every 50,000 miles that crap will never have a chance to build up. I will also be bringing the filtering parameters back to 100 percent of its intended capability. If it is lifetime fluid in a closed system there is no reason to check to see it has been overheated. That means if it has been overheated I could have a problem that could have been prevented. I am not saying you are wrong. I am saying neither of the sides can definitely declare victory. And, since I don't know the parameter based on the lifetime position and there are several reasons that the fluid can be compromised, and a fluid change is endorsed under those conditions, changing the fluid every 50,000 mi. could contribute to longer transmission life. Since there are so many that have had problems that instigate this never-ending debate--and the possibility of fluid degradation is there, and there is no proof it causes a problem --the side of conservative caution is very logically justified as well. . As you referenced we, who is we? |
I have no problem with changing the filter if the transmission feels "sluggish". But I will carefully collect the fluid from the transmission, strain it, and put it back in with the new filter and just top off with the proper fluid.
2002 3.0 X5 243,000 miles 2004 325i 108,000 miles |
Instead of listening to the marketing people from BMW you should follow the advice of whoever designed the trans, the engineers from ZF or GM .
I would guess that they would say to change the fluid at certain interval since as Engineers they know that to insure a long life for their products the fluid needs to be changed over a certain interval whether it be mileage or time. |
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The intent wasn't to declare victory. It is a debate for the sake of having a debate. The thread title was about thoughts on changing transmission fluid, and I only responded when I saw the old saws about there being no such thing as lifetime fluid, and that you have to change the fluid if you want to make your vehicle last. Those two aren't true IMO. |
Well you'd never know. Most manufacturers say their transmissions are sealed units with lifetime fluid. This is what they told me when I bought my Tacoma two years ago. It also says on the tranny pan of our X5's that they are sealed units. Engineers from BMW and ZF have done hours of testing to advertise the fluid lasting a lifetime. It's just a gamble on whether or not to change the oil. That's all.
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I thought I read somewhere that ZF recommends fluid maintenance on the X5 trans.
Let me see if I can find the article again. |
As for the price of $400 for the oil changed at the shop....seems a bit low if oil used was OEM ZF at $25 per liter X 16 (including torque conv) ...just the oil totaled $400....my transmission shop bill showed 16 liters ... Is somebody here can confirm that a full flush need 16 liters ?
ATF/Automatic Transmission Fluid By ZF OEM 1 Liter 5HPXXX |
The shop charged me cost for the fluid. Im sure they get it well below retail.
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ZF said they support the BMW recommendations as to service interval. They also said that for severe service, the fluid should be changed. I think the interval was 10 years, and some specific mileage, from memory. BMW is ZF's customer. They aren't going to contradict them. They are also going to take money from those who want to buy fluid change kits. They are not an independent bystander in this debate. We also need to keep in mind that ZF built the basic transmission, but that BMW did the transmission cooling system, and the integrated controls that back off engine power during shifts to reduce clutch wear. Also the torque converter lock up strategy. All of those impact transmission life compared to applications of the same transmission without those features. |
So which has the higher probability of failure?
Transmission A: 140K miles, original fluid, original filter, original gasket Transmission B: 140K miles, new fluid, new filter, new gasket |
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If the fluid has never been changed on either one, and it is then changed on B, then B has the higher probability of failure. If B doesn't fail in the next few thousand miles after that change, then it is back to equal. If we change the rules of the example, and change the fluid on B every 35,000 miles from new, then it doesn't have any significant increase in risk by changing it at 140,000. I'd give the benefit to transmission B in that scenario. Now we come to the payback question: If you change the fluid 4 times on B, will it last sufficiently longer than A to make the investment a smart one? |
So you're one of those people that thinks changing the fluid on a high mileage trans will have negative effects?
I'd love to hear the reasoning behind this one. |
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Transmission fluid, by design, has a high level of detergents. That is so that it lasts a long time. Over an extended time, those detergents become less effective. Varnish and deposits can start to build up in the transmission, in places where they are not doing any particular harm. Then, the fluid is changed, and those strong new detergents scour the internals of the transmission. The crud that is released and moved can make it to the filter. If so, fine, no problem. But if it first gets lodged in the valve body, in one of the orfices or check valves or actuators, it can precipitate a failure. There is a theory that this can also happen when the transmission is first filled, and started, and the fluid courses through, but I think the detergents matter more, as failures when they happen usually aren't on start up but in the weeks that follow. There is no such thing as shocking the fluid. There is simply cleaning out a system that isn't completely clean, and not having any place for the residue to go. Except through a valve body with a lot of very small passageways. If there is no failure within a few thousand miles (purely an estimate, no science here) I would say that a subsequent failure, if it occurs, isn't related to the fluid change. But if a transmission is working perfectly, and the fluid is changed at a higher mileage, and the transmission fails soon after, it is a recognized issue. We are not speaking here about the wrong fluid, or doing it wrong. And not about transmissions that already had a problem. In those cases, changing the fluid is a valid attempt to address the problem, and subsequent failures can not be blamed on the fluid change. The above failure mode is well enough known and understood that many shops will decline to change the fluid on a high mileage transmission that hasn't had a previous fluid change. They don't want to take on the risk. Because if the transmission fails, the owner will blame the shop and demand compensation. It is often better for their bottom line to just turn down those jobs and let someone else take the bullet. This has nothing to do with believing what the manufacturer says or not about changing the fluid. It is simply a risk/reward calculation. The way to reduce the above risk is to change the fluid frequently enough that crud doesn't build up at all. Some use the interval of 30,000 or 50,000 miles. I think that is a valid approach. It is just that if you are going to do four or five or more fluid changes before the transmission fails, you should be pretty sure that you will get a return on your investment. One change is pretty cheap. Four or five, not so much. And recall that if the transmission fails due to an electronic component like a sensor or wiring harness, as many do, or a random break not impacted by lubrication, then those multiple fluid changes will have been for naught in the economic analysis of return on investment. |
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My background includes a degree in automotive engineering from General Motors Institute in 1978, with lab experience with the original lock-up convertor turbo-hydramatic transmissions, and engines families including the Cosworth Vega, Buick 3.8L turbo, Pontiac Super Duty 455 and turbo 301. Along with ten years at GM assembly plants, I spent another eleven with Japanese and German HVAC Tier One automotive and truck suppliers. Count me as one who doesn't change fluid anymore. 2002 X5 3.0 243,000 miles 2004 325i 108,000 miles |
Transmission fluid thread. Must be Monday again.
Servicing the valve body (where the ball bearings wear) is beneficial. If one is beating the ever loving heck out of the transmission (Non-OEM software, more torque, etc) minding the fluid is beneficial. .02 Edit: Quote:
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I actually agree with JCL's point about transmission a and b. A transmission running on original oil doesn't necessarily mean it's bad and has a high risk of failure. BMW has done extensive testing with hours and hours of abuse to back up the claim that the oil is sealed. Transmission B can have a cheaper type of fluid or a cheap filter, which down the line can also cause a failure.
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One of yen things that has not always been clear is if the transmissions that failed also has their filters changed at the same high mileage. It's much easier to change the fluid only without the hassle of dropping the pan. Also a lot of the chatter is related to ZF trans. I can't imagine the gm trans being equally robust. This tranny is used in lots of gm vehicles including many Cadillacs.
I just dropped the pan and did fluid/filter t 98k. I guess we will see. |
I've got 243,000 miles on the GM transmission with no fluid changes and I average 3000 miles of personal watercraft towing each summer here in Texas. The only problem I ever had was dirt and moisture getting into the harness connector causing the transmission to go into failsafe mode.
2002 X5 3.0 |
A lot of this thread is covering ground members here have debated before (as J.Belknap very correctly notes). One of the better threads was here:
http://www.xoutpost.com/bmw-sav-foru...intenance.html Readers may want to revisit it for fun. Unless they can't stand to read more about transmission maintenance. Within that thread, post 29 included a link to a maintenance strategy document that challenged the paradigm that equipment is always more likely to fail as it ages. It is worth reading if anyone is interested in preventative maintenance approaches and how they are changing. The direct link is here: http://www.thealadonnetwork.com/PDFs/parUK.pdf srmmmm: With that experience, it would be fun to have a beer sometime. |
Email I received from ZF....
We stand by BMW’s recommendation of lifetime oil fill on the 5HP24 transmission. However to assure proper operation we advise to perform a drain and fill at 100,000 kilometers or after 8 years. We do offer oil and filters through our distributors. The only approved oil for your ZF 5HP-24 transmission is “Lifeguard Fluid 5” and the oil quantity required for a completely dry transmission is about 10liters. For the correct filter kit please go to genuine ZF parts.
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I think it would be a blast to have a beer with a few forum members. Some great debates take place on here and those debates always remain adult conversations, no insults are thrown like on some other forums. Tons of people on this board with tons of knowledge. That's what makes this one of my favorite forums to visit. We all share a passion for the X5 and everyone is always willing to give advice. |
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So ZF does recommend servicing the sealed transmission. |
I find it funny that the American car companies such as GM, Ford and Chrysler recommends an ATF change but doesn't provide a DRAIN in the trans pan, but BMW, and Audi provides a drain plug but doesn't recommend an ATF change.
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DuPage Auto Werks in west chicago. Best prices ive found for an indy german mechanic.
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I think we have flogged this long enough
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Friction is good for friction services. Level of friction is calculated for optimum performance and durability. Less friction is not good. The fluid and the filter become less effective over time. The degree of degradation may not be enough to cause transmission failure but changing the fluid every 50,000 miles means the fluid will be far closer to the initial specifications for optimum performance and durability. Even at 50,000 miles I don't think the fluid smells or feels like new. What source says---whatever you do, DON'T change the transmission fluid? |
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In terms of lubricating ability, we have seen reports (linked above) that oils actually lubricate better after thousands of miles than when they are new. That means less friction. For mechanical wear, that is a good thing. In terms of just the lubricating aspect of transmission fluid, I think the SAE papers are relevant. In terms of heat conducting ability, I don't think there is a significant change. And in terms of compressibility (ability to serve as a hydraulic fluid), ditto. So for two of the most critical requirements of an automatic transmission fluid, the fluid doesn't degrade over time. In terms of viscosity, I would expect the fluid to get thicker over time due to dissolved clutch material. The transmission has a built-in adaptation to that process with a feedback signal, so the fluid degradation in terms of higher viscosity doesn't matter until it goes beyond the transmission's ability to adapt. Now to filters. A filter that is partially blocked will tend to filter better in terms of particles stopped (because the passageways are smaller). There will be a correspondingly higher pressure drop, and potentially a reduced flow. The pressure drop doesn't matter until the drop exceeds the ability of the pressure regulation circuit to compensate. But the filtering efficiency (amount filtered per unit volume) will rise. Until the filter can not flow sufficiently. Then it needs replacing. My point is that a new fluid and filter isn't necessarily the best. They don't necessarily start out perfect and then degrade over their life. They can be designed to be optimum at mid-life, or at end of life (immediately prior to failure), depending on the characteristic involved. It is the same with many mechanical components. Interesting debate. And who says don't change the transmission fluid? That is a very broad question. I don't. BMW service manual reportedly does, up to 100,000 km if a technician has to drop the pan for another reason. Instructions I read were to reuse the old fluid. I say don't change the fluid if it is working fine, but it is the first thing to try (after checking the level) if the transmission is not shifting correctly. And I agree with your approach in that if you are going to change it, I think it is better to do it at shorter intervals than wait until 100,000 miles. That doesn't consider the value of changing it, just that it is a good way to manage the risk of higher mileage changes. |
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So, 10 years for normal use. Sooner for severe service. I'd put J. Belknap's supercharged 4.6 in that category, myself. |
I believe that JCL is on the correct path here. When I had a faulty wiring harness in the valve body that was causing shifting problems (not unlike a faulty MAF) the dealership per the TSB refilled the transmission with the fluid that came out of it. It was explained to me by the shop foreman that if all new fluid was introduced to the transmission it would shock it (the transmission that is) and could cause dislodging of sludge, debris, etc that would cause problems for the transmission.
If you do drop & drains at certain intervals, your likelihood of having issues decreases. |
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Did they flush the torque converter? That would require additional fluid.
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11 Litre is for a completely empty system. A completely empty system is when you replace the TC with a new or rebuilt TC. Sounds like the shop is padding the bill.
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First, I'm slightly confused why everyone thinks the transmission is a closed system. There is most definitely a vent pipe which allows for expansion/contraction of the air/fluids as the tranny heats/cools. If it didn't have this, every seal would start leaking very early in its life. The vent is higher up in the engine compartment and shaped to keep water out, but moisture and dust can get in there over time.
Yes, the filter does perform filtering function better over time becoming a super awesome filter, right before it becomes a perfect filter (100% filtering) at which point your transmission stops working because of lack of fluid flow. And yes, this will probably not happen until over 200k miles. But, lack of any maintenance before this happens, means that a fluid/filter change this late in life will result in all those varnish/deposits getting cleaned up all at once by the new fluid, and now you have clogged passages and valves, etc. So, new transmission or a complete rebuild (which is cheaper?) will soon follow the clogged filter. Same story applies for the viscosity increasing over time. Everything has to work harder, which is accounted for by the adaptations, until the viscosity can't be accounted for anymore at which point you start having shifting issues. This should be at higher mileage again, and change the fluid, it will shift better again, until the the new fluid frees up the varnish/deposits and you need a new transmission or rebuild. But, since there aren't many X5's out there over 300k miles that have regular 60k transmission servicing, JCL is correct that nobody knows what the actual life of a well maintained transmission will be. So maybe you spend $2000 in maintenance to get your transmission to last 300k miles. at which point it needs to be replaced or rebuilt. If you would have replaced the transmission at 200k without any servicing, you haven't really saved any money. And $1200 (3 fluid changes, 180k) over several years are lost earning potential. Now, if it can be proven that the fluid changes double the life expectancy of the transmission, it will totally be worth it. (neglecting the lost earning potential of the maintenance money) But, we need some guinea pigs to prove this case. And ideally, more than 100 vehicles doing regular maintenance to get some basic stats. Plus we need to find another 100 vehicles without doing any maintenance. And we need all 200+ vehicles to drive 400k miles. But, if you drive your car hard as in lots of redline shifts, heavy towing, etc, you definitely should look at extra maintenance beyond typical mfr. recommended. Everyone else, probably doesn't matter. |
obviously there are too many variables to do a consistent test. In my mind you would have
GM/ZF Miles change interval (if any) Fluid choice Driving style Filter/no filter enviroment. would be tough to get a one size answer for these. |
maybe include some people from the 5 and 7 series, although both are lighter vehicles and RWD only, so not that great for comparison with the X?
I thought about environment also, but even that has more variables beyond just weather and seasons like parking in a HVAC garage, carport/No-HVAC- detached garage, inclined driveway, or street at home, parking at work in a HVAC garage, no HVAC garage, parking lot, street. Or salt or sand for winter road maintenance? What types of roads they drive on and how often those roads are cleaned... I just realized I never gave my opinion, just a bunch of interesting points that didn't lead anywhere. Having a slightly different transmission in the 4.6, and the fact that the transmission was replaced at 60k, and had the fluid changed at 110k, I plan on changing the fluid again at 160k. But, if I was on the original transmission, at my mileage or any mileage above 100k, I would avoid changing the fluid and just wait for it to die of natural causes. |
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Reminder that the transmission vent is at the same height and almost same location as the differential vents...
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As I never partially submerged my X5, I didn't worry about that, whether for differentials or the transmission. If one is doing so, checking for water ingress would be a good idea, in all the compartments.
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Just for info., on the 5HP24 the air breather is mounted on top of the oil pump housing
http://i260.photobucket.com/albums/i...psdeb7b3fb.jpg http://i260.photobucket.com/albums/i...ps1f61d544.jpg http://i260.photobucket.com/albums/i...ps6892040c.jpg http://i260.photobucket.com/albums/i...psd56512c0.jpg Phil |
rrphil nice pic is that tranny out of a m54 or m62?
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The particular one in the photo is actually an '032' model from a Range Rover (M62 engine) but I am rebuilding an '034' model at the moment for a E53 4.6is if anyone would like to buy it when its finished :thumbup: (in the UK only I'm afraid!)
Phil |
For the record, I received a 'remanufactured' transmission from BMW CPO due to the 'thunk' issue.
I put a little over 30k on it including a 4 day blast in summer weather fully loaded from Vegas to DC and then a 3 day blast back 4 months later in early December. Add DC traffic for the interim four months (i.e., not an easy life) plus Vegas summer driving before/after. I just drained and refilled, no filter, etc. I used the Lifetime 6 fluid. Result was smoother gearshifts after the 6 or 7 liters (I don't recall) changed. The 'old' fluid was a noticeably darker color. Purely anecdotal evidence and I'm not trying to counter JCL's reasoning at all. My rationale for changing it was that it is easy for me to do (I have a lift) and I over maintain my stuff. It's not OCD, but it is likely clinically documented in the DSM… Oh, btw, 50 individuals would be a significant sample size for each side of the changed/not changed. Problem is that there are multiple different transmissions (2 at least) of the automatic variety… Or, we could employ Bayes' Theorem and go from there... |
so is there any step by step DIY to rebuild one of these trannys ,my tranny was just rebuilt in june of this year .I`m just curious how tranny rebuilds are done. :)
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Or maybe just organize a kind of survey from the forum member:
Question to all member who did flush transmission : how many got a fail transmission after the changed and how many went all good ?...adding some specific like : DYI or shop ? Milage ? Which oil Evaluation after 3kmiles...if we don't do something like this i.e get some stats ...this subject will last forever ... |
my theory in changing tranny fluid is this you have 200000 mile say on your tranny , tranny fluid is life time , but with that many miles tell me there isn`t any metal shavings in there, metal parts wear down no matter what so if you keep the fluid in there with all these metal shavings ,this is good for the transmission, don`t think so . so I`m the one that will do regular tranny flushes a piece of mind in my opinion. keep in mind metal doesn`t last for ever and will break down overtime.if its man made its not perfect.
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scary thing is that even with the advances in technology , fluid or mechanics, its still not possible for one of these "modern cars " to get the life expectancy of older cars,
it seems sad to me that these vehicles are built on a through away model. what was to bad about having to adjust the points gap, clean the plugs and tweak the mixture screws on the good old 4 bbl holley, AND occasionally check the oil in the turbo 400, as for the diff, never looked at it. same story with batteries, when i was young if i ever had to buy a battery it was a big thing, now anything over 2 years and your on borrowed time. seems sad to pay so much money for a vehicle that has such a relative short life expectancy my '94 XJ Cherokee has 400,000 km on it and has had the trans oil changed once, i can easily fix it and its super reliable, when i retire the 2005 3.0d X5 goes and i,ll keep the Jeep, and theres every reason to believe i will get another 200,000 out of it did a compression test on it and all cylinders were within 3 lb of each other so not bad after nearly 20 years |
The tranny in my 2003 began to shudder during shifts just after I bought it. I did a fluid flush first, then a flush and filter about a month later. It's been about a year since then and the tranny shifts like new, even after pulling my boat around all summer. Now that it has been done twice I will keep doing it at regular intervals to keep it fresh. With that being said, I had an auto tranny in my E36 that went 175k miles on original fluid and was still bright red when I drained it out to ship it. So I go both ways on this fight.
Sent from my iPhone |
I've got 244,000 miles on the original fluid. If I had serviced the transmission every 60,000 miles (fluid flush and refill plus filter for proper procedure), I'd have about $1600 in maintenance costs so far. A factory re-manufactured unit for my vehicle is $2245 which comes with a three year warranty. So if I can get to 360,000 miles without a breakdown, I'm money ahead to not change fluid for sure.
The question really is would those 60,000 miles servicings get me much past 360,000 miles before a replacement is needed anyway? 2002 X5 3.0 244,000 miles 2004 325i 109,000 miles |
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I used to like annual tune-ups and twice per year oil and lube services, they were good for the garage business. I think cars today are much more durable. If there are reliability issues in some areas, and there are, it isn't due to durability so much as it is a consequence of the complexity, not the quality of design and manufacturing, in many cases. The manufacturers accept that complexity, but we the consumers are the ones who insist on the latest gadgets and features. Just my $0.02. |
Fun with numbers
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I agree with your cash flow analysis but the problem is that in one of the above scenarios you end up with a new transmission with a three year warranty at the 360,000 mile mark, and in the other scenario you end up with a 360,000 mile used transmission with fresh new fluid in it. Those aren't equivalent situations, as one has greater utility. We can do a simple life cycle cost analysis, using the numbers provided, just replacing the transmission every 244,000 (assume failure tomorrow, worst case), vs servicing it every 60,000 in order to extend the useful life. You would have to make it 885,900 miles to reach the break even point, on a cost per mile basis. On the original transmission. Admittedly a very theoretical example. But this is the basis for the approach of not changing the fluid, and putting the funds saved aside for a future transmission replacement. |
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It is hard to do a payback analysis except by specific example and after the fact. Certainly at 244,000 miles on the fluid I wouldn't change the fluid regardless. That said, I do think a payback should include labor hours of what you think your time is worth, downtime cost and inconvenience, any shipping cost etc. Seems to me, per the forum, a great number of transmission problems that require going into the transmission happen between 75,000 miles and 150,000 mi. That would be the range of miles I would use for a pre-fail payback. I must admit that even if the payback wasn't there I would still change the fluid because until I have the cost and mileage after the failure of my transmission, my calculations are only a projection, they aren't an actual, accurate payback calculation that means much if anything. There are changes in some years of a given transmission and within the E53 years different transmissions. Also, these transmissions are coupled with different engines. As an example, I have a 2002 4.6 with 110,000 mi. on the original transmission. I have changed the fluid every 50,000 mi. A projected payback should only be with like vehicles where the transmissions have had internal problems--using those costs and miles to calculate a potential payback comparison for me. What I think is very unfortunate about the--to change or not to change, that is the question-- fluid threads, is, at least for me, I never have a clue if we ever get close to something that is apples to apples. I am not able to conclude what transmissions are prone to what problems. I assume some are better than others but it is not clear how they individually rank. Because of that, I come away thinking all E53 transmissions are very poorly engineered and subject to premature failure. Because there are so many threads about transmission problems, I am constantly expecting mine to fail, especially since I am stressing it far more than the norm for a stock 4.6. The worst case of these threads is I believe we cause some newbies to think they have just made a terrible purchase--doom and gloom is at redline heading their way. |
[QUOTE=bcredliner;966799]I would like to meet the person that is putting funds aside for a future transmission failure--talk about a half empty glass.
Because there are so many threads about transmission problems, I am constantly expecting mine to fail. Even though the X5 is paid for, I still transfer about 50% of the monthly payment I had into savings to cover repairs & maintenance. As long as the balance stays positive, I'm happy. The failure point I fear is losing the splines on the front driveshaft again...while pulling the boat out of the water. I've blown the tranmission in my Firebird and Bonneville diesel multiple times, and even though I might have lost a gear, or even cracked the flex plate, the vehicle wasn't totally immobilized. Driveshaft splines are a different story though. By the way, the Allison 4000 series transmission in my father's 44ft motor home calls for 50,000 mile filter change intervals with a fluid top-off, but no complete fluid change for 500,000 miles! 2002 X5 3.0 244,000 miles 1004 325i 108,000 miles |
Can't fault budgeting for maintenance and repairs, great to do. You would be close to that one person if your budget for repairs was specifically for front drive shafts.
That said, the thread is about transmissions. My points are concerning the specific topic of transmissions and stemming from forum threads. As I mentioned, I can't discern what problems happen to what transmission--or when it is apples to apples based on what engine package. I do know that an Allison transmission for a 44ft. motor home is not apples to apples. My position pays no heed to recommended service intervals. It is my position that changing the fluid every 50,000 cannot currently be dismissed as illogical. If there was a tag on my transmission that said--WARNING WARNING--DO NOT CHANGE THE FLUID FOR ANY REASON. CHANGE OF FLUID WILL RESULT IN PREMATURE TRANSMISSION FAILURE!!!, at that point the there would be no difference of opinion--well maybe there wouldn't. FYI-If I were towing a boat with my X, the boat wt. would be under max. towing capacity, I would drive like I have an egg under my foot and not be concerned about tearing anything up. |
Don't worry bcredliner, I rarely mistake my father's motor home for an E53 -it's a little clumsy maneuvering on some of the boat ramps we use! The observation was just that modern ATF fluids have a very long life if not overheated or contaminated. You're right about that driveshaft. It was a $4200 deficit, even with a used transfer case.
2002 X5 3.0 244,042 miles (today) 2004 325i 109,000 miles |
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I would not dismiss changing the fluid every 50,000 as illogical. Illogical is a strong word. I do think we are mixing up two different issues here though. 1) If the fluid hasn't been changed in a long time (pick your interval....) then I believe it can be a risk to change it. Doesn't mean it will fail after a proper change, but there is a risk. I would avoid that risk if I could. The first and most obvious way to do that is if you are going to change it, then to change it more frequently. I think that if you are changing it every 50,000 miles you have far less risk than if it went double or triple that. In that sense, your specific fluid change regime is not illogical at all. 2) If the fluid is being changed because of an economic proposition that doing so will pay the owner back for the cost involved, whether by causing the transmission to last longer or perform better up until eventual failure, I think that is overly optimistic. There are too many failures due to non-fluid related causes, and when that happens then everything spent on fluid changes is thrown away. The lack of system reliability we have seen suggests that planning to run a transmission a very long time simply by changing the fluid is illogical. |
Dinan tranny software saved my transmission! I was getting a check engine light periodically for the common P0741 code (torque converter lock up issue). Since the addition of Dinan software I haven't seen it once. Shifts stronger and faster too.
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:iagree: with number 1 I don't know whether to agree or disagree with 2. What you mean as a very long time may be quite different than my view. I don't know why I would include failures not related to fluid in a payback calculation about worth of changing fluid---has nothing to do with fluid, has nothing to do with this discussion. I do change the fluid for the purpose of better performance and reliability. I don't think anyone has enough facts to substantiate lack of logic or over optimism abut that. I know that I don't. That might be the case if the posts about transmission failures were more detailed and both sides of the debate were posting equally. Lumping all the repairs for any transmission results in my current perspective--- somewhere after 75,000mi. I am likely to have a transmission problem. if I make it over 100,000mi. I am in the minority. It's the best guess I can make but it not anything to make a decision from because I am not comparing 4.6 transmissions with mine. |
Hmm... how hard is it for a low-skill wrench-swinger to change the trans fluid?
Going to save for a rebuilt either way, jic. ;) |
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But if there are a lot of transmission failures not related to transmission fluid (and there are reported to be), then we need to consider that information. Owners that have a failure (for non fluid related reasons) will have to tear into the transmission anyway. The opportunity for benefit is reduced. Essentially, it comes down to the newer fluid being potentially good, but irrelevant. |
Funny...
I was just thumbing through my owner's manual. It clearly states.. Automatic Transmission Service: Change ATF every 100,000 miles. So BMW does recommend servicing the automatic transmission. |
It depends on the year of manufacture. They flipped back and forth, not necessarily on the same transmission models, but on the same base vehicles.
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I thought you meant none fluid related failures---failures where no fluid is present. As an example-software. I agree that a payback should include the cost of the fluid/filter change. And, the cost of fluid change added to cost of transmission repair. Unfortunately, it doesn't matter what we include-- a payback calc is meaningless because we don't have enough information to make it accurate--I wish that weren't the case. I don't consider a payback calc as an endorsement to change or not to change fluid. The bottom line of this payback would be cost per mile. Since there are no min/max mileage for transmission failures or average cost of repairs we are talking gobble-de-gook. The primary question--is there a potential or real benefit to changing fluid or not. Obviously, since we are having this discussion we don't know if there is a real benefit. As to potential of a benefit, I think the answer is yes. As to the question, is it a waste of time and money, nobody knows. What we do know is that we replace oil and other fluids because they degrade over time and they all have a maintenance schedule. (I find it hard to think of anything that doesn't degrade over time). We know that BMW recommends to change the fluid if it has been overheated. We know that BMW has both suggested to change the fluid at 100,000 mi. and have said the fluid is lifetime fluid (whatever that is---when is a X5 considered dead?) We also know that BMW has not said--whatever you do, don't change the fluid because it will cause the transmission to fail. Add to this that we hear about enough transmission problems that many of us are concerned about transmission reliability and longevity. Personally, that means to me it is a good idea to do something that logically could extend the number of miles I drive before I have a transmission problem. And, if I do have a problem it could cost less to fix. And, something so I don't hesitate to stomp the go pedal and fire the nitrous. As it relates to the fluid is so much better than it used to be--OK. That it gets better as it ages---not OK--not apples to apples, might as well have been a used mayonnaise study. Though if anyone wants the fluid from my next 50,000 mile change, I will sell it at 50% of the cost new, plus shipping. |
Agree completely that we don't have enough information to do a precise payback calculation. But if it can be shown that the cost and benefit lines diverge, ie that they never meet in practice and so there is never a payback, then it doesn't need to be precise in order to have some value in guiding our choices.
Nobody said the fluid was going to last the lifetime of the X5. It never referred to the vehicle's lifetime. We are talking about the transmission's lifetime. And the reason BMW said not to change it is that statistically, the transmissions failed before the fluid wore out. That is the essence of the argument that there is never a payback. That you can change it all you want, but it is more likely to fail for non-fluid related causes, so unless changes are free, doing them as PMs is a questionable proposition. Again, the fluid doesn't get better as it ages. But it can be argued that the lubricating qualities of the fluid, being just one of its key characteristics, do get better. If you refer back to the maintenance philosophy document I attached, it points out that in complex systems, failures often aren't more likely with age. That isn't intuitive either, but it is more and more true these days. So the maintenance practices based on older paradigms often don't make economic sense. All that said, if I was putting significant shots of nitrous into my X5 and thus operating its transmission beyond the design parameters, I would probably be changing the fluid regularly too. |
Transmissions failed before the fluid wore out? Any scientific evidence to prove that the fluid in these failed transmissions was up to spec? Or is this just another guess? If not broken down fluid or contaminants, what exactly caused the failure? Go ahead, make more guesses.
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The largest contributing factor to failures in complex systems is the complexity itself, not wear. Wear is generally predictable. A wide scatter of failure points strongly suggests causes other than straightforward wear. It isn't generally necessary to prove fluid quality for failures not related to fluid condition. That is a scientific approach. No guessing required. |
I guess to each his own.
I've owned numerous BMW's, always did trans services and I have never had a BMW transmission fail on me (knock on wood). So from my own personal experience, I will continue to service my transmissions every 100k miles per my owner's manual. |
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Your position is the cost of fluid(s) changes may not be offset because of other failures that require replacement of fluid anyway. And, since very little lubrication is needed in a transmission and the fluid is said to be for a lifetime you are on the side of don't change the fluid as there is no benefit/payback. In short, don't bother changing the fluid because the transmission will fail before there is any fluid related wear--- I think I got that right. Until there is long term research, a controlled study, with set parameters that result in graph plotting the failures at what miles, including notations of any worn parts fluid related regardless of the type of failure and associated costs at a set labor rate there is nothing scientific about this discussion. It is all about what logic you subscribe to. My logic is it can't hurt and and it makes sense it should help... that coupled with my personal experience where I have always replaced the fluid at least twice as much as specified depending on how much I was pushing the performance from high performance engines. Since we are talking E53s using only the particular X transmission I have, it is still as good as new at 110,000 sitting behind a modded 4.6 with 150 shot of nitrous. What is your version of logic for not changing the fluid? Perhaps we can conclude this debate with that? |
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I don't see a difference in lifetime of a transmission and lifetime of the vehicle as I always need a transmission. Lifetime means to me that as long as it can be repaired it is not dead. Where does BMW say the transmission will fail before the fluid is worn out? Even if that is true, I would be flabbergasted if BMW ever let that out. Are you basing your opinion that fluid gets better on the study of oil in a diesel engine? Don't I recall a post where you said engine oil and transmission fluid are entirely different? Failures often don't happen more often with age? X5 transmissions are as likely to fail at 10,000 miles as 150,000 miles? Dinan mods increased torque to peak of 371. As you know, adding a 150 shot of nitrous will increase torque as much or more than HP. Since you agree I should change the fluid, My take is it is not a question of if but when fluid should be changed. As you said, fluid doesn't get better with age. To me, it doesn't really matter which key characteristic doesn't age well. My position is in a stock configuration before 50,000 miles, the fluid is not performing as good as new so change it because it is there to control heat, provide lubrication and make the transmission shift as it should. Doing anything less is decreasing the number of miles before I have an issue. And I don't understand why I should be satisfied and comfortable with a transmission that is not at peak performance and one I haven't done everything I can do to contribute to durability. |
Well, I think we are starting to just repeat previous posts, but here goes.
If I had a heavily modified X5 with more power being put down than BMW ever designed the vehicle to handle, I would say all bets are off. Normal maintenance rules don't apply. Neither is the experience gained with that vehicle appropriate to apply to stock vehicles. You are outside the design parameters. Do whatever feels good. Changing the fluid may make it hang together longer. I have no idea. It is a sample of one, and that doesn't tell us much. I don't agree that aged transmission fluid by definition does not perform as well as new fluid. It can certainly do so, if it hasn't been overheated or contaminated. It doesn't wear out unless it is overheated. It will change over time, agreed, primarily in the amount of additives that remain. That is to be expected. I think you are suggesting that if the fluid is less than new, then the transmission won't be working as well as it should be. I don't agree. The transmission was designed from the start to deal with a fluid that ages and changes properties. The feedback loop for clutch engagement times (measuring frictional characteristics) is an example. The transmission can also deal with widely varying fluid viscosities. Those features were designed in so that the fluid could age and not impact transmission performance. It is why the transmission has adaptations stored; it is adapting to fluid condition and its own performance. The diesel lube article was in response to numerous claims in this thread that all fluids wear out, and that new fluid is always better. That turns out to be a false claim. Yes, I used data about engine oil, but it seems only fair, since some posters continue to use engine oil replacement as a proxy for transmission fluid changes, and talk about making the mechanism last longer from fewer metal particles in the fluid. I think that if we want to justify a transmission fluid change we need more than "because it is right to do so". At the same time, I think that people should do what they want to do with their own transmissions. I am not attempting to talk people out of changing their own transmission fluid if that is what they want to do. I am saying that they should recognize that justifying their strategy with "because it is obvious" and simultaneously putting down others who don't share that strategy isn't logical. I don't like reading attacks such as "what happened to pride of ownership" and "if you cared about your vehicle you would..." A look at when components fail can tell us something about the common failure modes. If the failures are all grouped in a bell curve, then wear is worth looking at, because wear should relate to use (miles, hours, number of shifts, whatever). If the failures are all over the place, from 30,000 to 250,000 miles as reported here, then logically something else is going on other than straightforward wear. There are maintenance management strategies that study that phenomenon. I attached one. All I am saying is that metal wear is not likely to be the primary cause of transmission failure. I know that many like to say that these transmissions tend to fail at 100,000 miles, but I don't agree with that conclusion. I think they fail at all sorts of mileages. And the random nature of the miles to failure in itself contains a clue to the cause. I think it is complexity. It is the famous o ring seal. The actuator. The snap ring. There are a myriad number of failures. And they occur in transmissions from two different non-BMW manufacturers, in three different X platforms that I follow. We don't have statistical data, agreed. We have frequent anecdotal reports of transmission failures. But do we have reports of failures caused by fluid degradation? The first sign would be burnt fluid. Not much reference to that in the almost nine years this board has been running? Any burnt transmission fluid, when not caused by another failure, like an actuator? Any apparent higher incidences of failures when towing trailers up to 8300 lbs? We even have people here with nitrous and superchargers. Are transmissions failing at a higher rate there? If the failures were mechanical wear, increased load would cause earlier failures. And if the fluid was wearing out at 50,000 or 100,000 miles, it should be pretty much impossible to get to 250,000 miles. Just as a reality check, we haven't seen many reports of engines needing rings and main bearings either, despite the fact that most X5s follow factory maintenance recommendations. We just aren't seeing mechanical wear dominate the failure reports as we used to decades ago. That is what should cause us to challenge previously held positions about what are appropriate maintenance strategies. Since the thread was titled "Thoughts on changing transmission fluid" I figured it was an open discussion. I didn't think there was supposed to be a winner. There certainly isn't a single right answer. But there can be some new food for thought. |
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FYI--BMW defines lifetime fluid is as -- for the usable life of the transmission. :iagree:. If it hasn't been said and responded to by now it most likely doesn't matter. I welcome you to make the last post. Disclaimer--all of my posts in this discussion are nothing more than my personal experience, derived from reliable sources or forum posts resulting in what seems logical to me. It is intended to be nothing more than constructive input. |
Dallas: I don't think you attacked at all. I was referencing this and many similar threads over the years.
Cheers Jeff |
Damn. I gave up on these threads lol. Glad you still at it JCL. Makes for a good read when the boredom sets in.
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So what we got out of all this back and forth banter, is that it's a matter of personal preference and what gives you peace of mind.
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I actually owned a 3.0 X5 with the GM Powertrain transmission. Those technical documents described a very similar adaptation routine, jointly developed by BMW/Siemens/GM, and used for adaptive pressure control (APC) on those transmissions. These sorts of control strategies, with their learning capabilities, are at the heart of why fluids last much longer. IMO. There is another side comment, which is that understanding what the adaptations do, it makes no sense to reset them without first changing something that caused them to be at the values they are at (like a transmission or a solenoid). When people reset the adaptations because they think the adaptations are the actual problem, they are masking a symptom, not fixing something. People seem to like to reset them, though. |
I'd like to see that original document, because what you posted states absolutely nothing about the transmission adapting to deteriorating fluids.
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If people want a singular truth and to gain enlightenment, anonymous posts probably aren't the best format IMO. |
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There is another document posted up here somewhere that talks about the x drive transfer case. That has adaptations as well. And the control strategy is exactly the same, clutch pressure is modulated based on feedback signals. In that component, when the adaptations reach their limit (no more ability to correct for fluid properties as they change from time to time) you get a light on the dash saying fluid is out of spec. Not that clutch plates are worn, but that fluid is out of spec. Exactly the same principle. Edit: Quoted ZF transmission document: http://www.e38.org/electran1.pdf. Still looking for the original one. |
By request, a summary of the adaptation capabilities of the ZF transmission. The easiest document to search on was the ZF patent, so here is one of the main ones. Related patents are linked on the page.
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Brandon: I humbly submit that fluid condition as it changes over time is an influence which can impair a gear shift of a wet clutch pack (each clutch pack forming a shifting element). I think we agree that fluid quality over time is an influence. ZF got a patent based on adapting to each influence. Ergo, they are adapting to fluid quality, not by direct analysis of the fluid, but by measuring the performance of the fluid. Patent linked here: Patent US6569060 - Method for controlling a transmission of a vehicle - Google Patenter Interesting side note again: The patent references a specific benefit of adaptive pressure control, namely that transmission manufacturing cost is reduced due to the ability to open up the manufacturing tolerance limits. Those tolerances can be opened up because the adaptive pressure control can handle wider tolerances than a 'dumb' system. We often think of modern vehicles as being much more complicated (which they are) and at the same time more precise, which would mean more demanding on things like fluid specs and quality over time. Here is a case where precision was reduced, intentionally. That intuitively fits with the transmission being more tolerant of varying fluid condition, which is where this discussion started. |
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It means "more tolerant" of fluid condition.
Nowhere does it state that the condition of fluid won't have any negative impact on the life of the transmission. How long will it adapt before it can adapt no longer? Again, it's an argument that can go on forever because there is no concrete, technical data to prove one theory or another. |
Explaining how the transmission adapts is helpful and interesting-thanks for posting. That's is more detailed than I have read.
I am not challenging that fluid can be used a longer period of time if because of the fluid itself or the ability of the transmission to adapt to fluid performance. My position to change the fluid is based on fluid degradation over time. I have explained how I came to that conclusion so I don't think there is any need to do it again. The adaption capability is a great feature to extend transmission performance. As I read the how and why the transmission adapts, it also appears to endorse that part of the reason the transmission has the ability to adapt is the fluid does not perform as well over time. That when the transmission can no longer adapt the message is that the fluid is out of spec seems to be additional input that fluid degrades. I picked 50,000 miles for a change interval out of the air. My logic is the fluid has lost enough performance that new fluid will be a worthwhile investment. I know there is not enough reliable information to verify that point of view. On the other hand, I don't think there is enough reliable information to take the position it is a bad practice. I don't think you have even implied that either, have you? Just as you said it could be a good practice based on what I drive, it may not be worthwhile if the engine is, say, a 3.0. If I had a 3.0 I would at least extend the interval but check the fluid as often as I do now. I don't believe in resets either, updated software yes, resets to fix a problem-- natta. Brandon, I don't see this as banter. I think it is constructive. I respect JCl's contribution and I believe he does mine. I don't take it personal, do you? |
I don't take anything on the internet personally.
I used banter as a term, I too find it informative. |
Guys, maybe i'm too naive but the data that we are looking at is not right here throughout all Forum Member experience / transmission issue or not ?....we reach 350k post from thousand of members.
I'm not the best to build a scientific or valuable survey (maybe JCL ;-))...but hey ! that would a good start no? |
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Bryan |
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