Let's talk Transmission Maintenance...

[genew]

Originally Posted by ard

Good point.

So all we can hope to do is bring the issue to people's attention- so they can consider whatever facts exist- and they can make their own decision.

Instead of only blithely following their CBS indicator on the dash (which won't unfortunately tell them to change ATF at any mileage)



A

PS If you know that engineer's email, PM it to me.... thx

(I kid)

This won't help you in any way but thought I'd throw a couple of facts in. I have driven over 105,000 miles in an e53 2001, and 110,000 miles in an e53 2004 and the original tranny fluid was in both and the transmissions were shifting perfectly. Have 35,000 on an e70 and the same.

[ICX5]

Interesting points on both sides of this issue.

I believe all parties agree that with a lack of actual technical data around the transmission operation, wear, fluid degradation, etc., then empirical data becomes a major source of information. But even here, when speaking specifically about BMW transmissions, we have a lack of actual data. Sure, there are folks with actual experience with transmission failure or friends who experienced it (so one, two, maybe five data points), but what of the million plus units that BMW and their suppliers have put out to date?

Is there consideration to any "motives" that BMW might have in recommending extended servicing of the transmission:

1. BMW wants your transmission to fail as soon as possible so you will buy a new car sooner?

2. BMW doesn't want the income (or more accurately the dealer's income) that would be generated by servicing the transmission every 5,000 miles, 10,000 miles, or whatever mileage number you'd like to insert

3. BMW believes their engineering staff in that the transmission doesn't need regular servicing of the fluid (again, the term regular seems up for debate). Perhaps the engineers are using a balance of technical and actual field data. Maybe the engineers were tired that day and just guessed?

I think this list could go on and on, but I find it hard to believe that BMW choose the recommended service interval for no particular reason (good or bad).

If 5 out of 10 BMWs were experiencing transmission failure at 50,000, 60,000 or even 100,000 miles, you would think the word would be more widespread.
I'll be the first to admit, I haven't been following BMW drivetrain reliability over the past years, but by the looks of some of the BMW owners on this forum and the number of posts (length of membership), there should be some word of transmission failure problems if it is occurring. Perhaps the majority of members are not keeping their cars much past 100,000 miles, but I think some history would still show up.

[Halston Pitman]

BMW used to say it was a 15, 20, 30 and 40K service on various components... like back when they wanted people to think their vehicles lasted forever. I know of 2 300,000 mile E30s with original automatic trans.

Now it is lifetime or 100,000 miles. BMW has changed to what I deem a recycle me car. 100K and it is time for a new BMW. If you follow that schedule you are looking at a much longer lasting vehicle. Diff fluid, coolant flushes, trans fluid etc all needs to be changed at regular intervals. BMWs will push 15K or more on oil changes. No thanks

[Lubehead]

BMW does not manufacture the transmission, ZF does. I do not believe BMW has "motive" other than to provide the highest level of technology available with regard to most major components of the vehicle especially the drivetrain. ZF engineers have evidently come to the conclusion that their product (and their good name) is well served by the recommendations they have published.

JCL's reference to the transmission as hydraulic system is spot on. And his message regarding its comparison to an engine is relevant and factual.

In industrial applications many OEM's continue to recommend drain intervals that are not relevant to today's superior performance fluids and most certainly do not pay attention to the reliability engineer's focus (and industries movement towards) condition based fluid change intervals as opposed to time or mileage based oil change intervals.

BMW/ ZF are I am sure, cognizant of the characteristics of the fluid as well as the dynamics of the wear mechanisms occurring in the transmission itself. In hydraulic systems especially, it is well known that particulates in the fluid damage system components and yet there are plenty of maintenance personnel who believe they are doing good by the machines they are responsible for by changing oil because it has achieved a certain length of service time, when in fact the opportunity to do more damage as JCL suggests, is real and in fact counterproductive to the machines life. Heavy equipment OEM's are well aware of this and ZF is a vendor to that market as well.

As far as the BMW/ZF transmission itself, the only improvement I would like to see would be an oil sampling valve somewhere on the transmission or its cooler lines. This valve (which would cost no more than $10.00) would enable monitoring of the fluid without opening the unit to the atmosphere. They are commonly installed on heavy equipment hydraulic systems, transmissions and many industrial hydraulic systems. Fluid degradation, contamination, viscosity, etc could easily be monitored and action could be taken as analysis results dictate.

[ard]

Originally Posted by Lubehead

BMW does not manufacture the transmission, ZF does. I do not believe BMW has "motive" other than to provide the highest level of technology available with regard to most major components of the vehicle especially the drivetrain. ZF engineers have evidently come to the conclusion that their product (and their good name) is well served by the recommendations they have published.

What does "well served" actually mean?

Do you mean that ZF believes the longest service life will be achieved by not ever changing the fluid?

Or has this become a calculus of 'ownership costs' and 'owner hassle' and 'likelihood of trade in' combined with odds of failure to determine this is 'best'?

(Much like the way a recent panel of womens health experts determined that mammograms are not recommneded for women under 50, since the false positives are worrisome, and cause more biopsies- even if it does save lives?)

JCL's reference to the transmission as hydraulic system is spot on. And his message regarding its comparison to an engine is relevant and factual.

I do agree. There are wear components in a tranny though, so it isn't JUST hydraulic... and admittedly engines are hotter, fuel shear more of an issue as is contamination via combustion products. But my argument was that you rarely hear of "oil falure" as a cause of engine failure- would this lead one to believe oil doesn't need to be changed? It was an argument taken to abstraction.

In industrial applications many OEM's continue to recommend drain intervals that are not relevant to today's superior performance fluids and most certainly do not pay attention to the reliability engineer's focus (and industries movement towards) condition based fluid change intervals as opposed to time or mileage based oil change intervals.

BMW/ ZF are I am sure, cognizant of the characteristics of the fluid as well as the dynamics of the wear mechanisms occurring in the transmission itself. In hydraulic systems especially, it is well known that particulates in the fluid damage system components and yet there are plenty of maintenance personnel who believe they are doing good by the machines they are responsible for by changing oil because it has achieved a certain length of service time, when in fact the opportunity to do more damage as JCL suggests, is real and in fact counterproductive to the machines life. Heavy equipment OEM's are well aware of this and ZF is a vendor to that market as well.

I'd like to think ZF & BMW have ONLY the longevity of the AT assembly as their sole determinant as to the fluid service. Until that is confirmed, I thin the community is ill served by broad assertions that 'high tech' fluids will save the day.

I can find NO DATA that says regular preventative maintenance will damage transmissions. Plenty of data that neglected transmissions are ill served by late services and flushes. I'd like to separate these two concepts.

As far as the BMW/ZF transmission itself, the only improvement I would like to see would be an oil sampling valve somewhere on the transmission or its cooler lines. This valve (which would cost no more than $10.00) would enable monitoring of the fluid without opening the unit to the atmosphere. They are commonly installed on heavy equipment hydraulic systems, transmissions and many industrial hydraulic systems. Fluid degradation, contamination, viscosity, etc could easily be monitored and action could be taken as analysis results dictate.

Personally I suppose I agree, but I need to ask you "why?" Isn't the BMW interval of 100,000 miles satisfactory?

[JCL]

Originally Posted by ard

There are wear components in a tranny though, so it isn't JUST hydraulic... and admittedly engines are hotter, fuel shear more of an issue as is contamination via combustion products.

What is fuel shear to which you refer? Are you referring to fuel dilution? Or viscosity reduction due to fluid shear?

[m5james]

Let's beat a subject to death IMHO, the best way to get a nice and long lasting transmission is as follows...


1) Dont warm up the engine then drive the truck hard once you leave the house, remember - the tranny is still cold. My E34 M5 (currently have) and my E39 M5 (sold) even suggested this in the owners manual, as well as the E39 having a redline changing tach until the engine is up to temp, which serves two purposes.
2)50k filter changes using ONLY BMW or Filtran filters, and don't forget to clean the magnets
3)50k fluid changes using either BMW suppled Esso ($20-$35ish per quart), VW supplied Esso (like $15 per quart, close enough to the same stuff), Valvoline MaxLife (Esso compatible, 1 gallon for like $10-$15), Redline D4 ATF (like $10-$15 per quart) Castrol Import Multi Vehicle (the only dyno oild that is Esso compatible, like $6 per quart). I've said it before, and I'm sure the OP can agree that there is absolutely NO fluid that doesn't degrade over time. Period.


I have an E53 X5, so I don't have to worry about the whole tranny resetting thing that killcrap referred to.

[ard]

Originally Posted by JCL

What is fuel shear to which you refer? Are you referring to fuel dilution? Or viscosity reduction due to fluid shear?

I was specifically citing issues that would happen in a motor versus a transmission- so I was referencing "fuel dilution" and the resulting reduction in viscosity. (So fuel shear is a shorthand term...) This is different than mechanical shear or VI shear that will occur in any mechanical assembly.

[JCL]

Originally Posted by ard

I can find NO DATA that says regular preventative maintenance will damage transmissions. Plenty of data that neglected transmissions are ill served by late services and flushes. I'd like to separate these two concepts.

I only have my own experiences, I mentioned them previously, but I haven't published anything on it, so I'll leave that aside. Lubehead did make several references to heavy equipment, and that is where much of my experience has come in the past 20 plus years. We (as an industry, not just the manufacturer I work with) have maintenance programs that are generally much more advanced than typical automobile maintenance recommendations. I didn't invent any of them, I just work with them.

A couple of observations, apologies if I am prescribing opinions to you incorrectly. a) You base your maintenance plan on the assumption that the transmission is more likely to fail as it ages. This isn't necessarily true, over the life of the asset. b) You are looking for hard data ,when it doesn't exist. c) You promote a generic maintenance schedule, ie a fixed fluid change interval.

I have attached an article by an organization that teaches how to determine maintenance requirements of a physical asset. It seemed appropriate. Apologies if you have read it and are familiar with it. The three points above are covered in the article. I also think you will really enjoy maxim #14 in the article, which is all about not blindly following the equipment manufacturer's recommendations. Yes, I can see both sides of an issue

Incidentally, the article is 15 years old, ie years before the first X5 was manufactured. This stuff isn't new. Hope some here find it interesting.

Maintenance Management - A New Paradigm

[FSETH]

Originally Posted by JCL

My lack of support for changing the fluid is not because "BMW said" but rather because I see little benefit to changing it, and a small but real risk. The risk of damage is slight, but it exists. At the same time, I think that the transmission is likely to fail from non-fluid related causes prior to the fluid degrading to the point that it causes a transmission failure itself...

There are members here with transmissions far beyond 100,000 miles, on the original fluid. What that really means is that other things haven't broken yet, and the fluid has just soldiered on.

This entire post by JCL was great, IMO, but the above comments stood out the most to me. I appreciate you pointing out that fluid changes DO come with a small, but real risk. I think some people have a hard time believing that. What you say makes sense to me personally, but then I don't have any hard data to back it up. I take your word for it as someone who seems to have extensive knowledge and experience in this arena.

I also agree that there are simply way too many 100,000+ mile X5's rolling around out there that are on original transmissions and fluids for me to think that a breakdown in fluid is the main cause of BMW trans failures. For every person with over 100k miles on original fluid there is another who's trans failed under 50k miles. It seems as if the age of the fluid is inconsiquential to the life of the trans in most cases.

Quicksilver also made a good point that people are going to do what they want to do when it comes to this issue. At the end of the day, do what makes you happy. Just dont think that changing the fluid is going to prevent trans failure and realize that there is a small risk in doing so. It is not always that new fluid = better in an auto trans.

For what it is worth, I have an 02 4.4i with 109,000 on the original trans and fluid and it runs fine (knock on wood). I also have an e36 325i with 303,000 miles on the original automatic trans. I bought that car with 100,000 and have changed the fluid 3-4 times over the past 7 years or so. Started slipping a little between 2-3 gear about 60,000 miles ago, but it has been soldiering on.

I would be curious as to what the average lifespan for a BMW automatic transmission is these days anyway. I bet it isn't that much over 100k. BMW probably doesn't see any reason to recommend changing the fluid before that mark because they know that the original fluid will last the average trans lifespan anyway.