Thoughts on Changing Transmission Fluid

[JCL]

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.

[Brandon002]

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.

[JCL]

Originally Posted by Brandon002

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.

Well, how about all transmission electrical failures (sensors, wiring harnesses, etc). Actuators. Torque converters. Broken snap rings, if the failure was not consequential damage due to another component with too much play. Valve body failures related to springs, check valves, etc. Bearing failure where a single roller bearing has failed completely, while all other bearings are in good shape (thus eliminating fluid as a likely cause). This list goes on. In general, any transmission failures not involving worn clutch plates or worn metal throughout the system.

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.

[Brandon002]

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.

[bcredliner]

Originally Posted by JCL

Well, how about all transmission electrical failures (sensors, wiring harnesses, etc). Actuators. Torque converters. Broken snap rings, if the failure was not consequential damage due to another component with too much play. Valve body failures related to springs, check valves, etc. Bearing failure where a single roller bearing has failed completely, while all other bearings are in good shape (thus eliminating fluid as a likely cause). This list goes on. In general, any transmission failures not involving worn clutch plates or worn metal throughout the system.

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.

The point of this discussion is to change or not to change fluid. For simplicity, include all transmission failures. We are still without anything that determines which way is the best.

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?

[bcredliner]

Originally Posted by JCL

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.

There is no way to know if the lines meet or not unless we know what part of any failure was non fluid related and what was replaced because of fluid related wear. As an example, If a transmission was repaired after a significant amount of miles but the cost was less because there was no need to replace fluid related wear parts and the same transmission with original fluid failed and fluid related wear dictated replacement of more parts the lines could cross.

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.

[JCL]

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.

[bcredliner]

Originally Posted by JCL

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.

Testing of products includes includes extreme conditions. One of those extremes is in the real world, taxing the mechanism beyond normal use.That is part of the way specs are established. In the case of a transmission a supercharged or nitrous added engine would be appropriate.

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.

The additives are there for a reason. If they become less effective the fluid is less effective Yes, it may be good enough but it is not as good as it was for the transmission when it was new.

Per the Bentley manual the first sentence of troubleshooting an E53 transmission reads: "Minor automatic transmission problems may be corrected by changing the automatic transmission fluid (ATF) and filter." Paraphrasing, it goes on to say one of the reasons it might help is the fluid has overheated but it can also be clutches burning and the friction material released has clogged valve body passages.

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.

I am not making declarative statements. I am only presenting what is logical to me. As an example, if the transmission has to adapt to fluid changing properties, I draw the conclusion it is not as good as it was when new. I acknowledge there could be another side of the coin but don't have anything to that I consider as endorsement.

Would you post the source of the adaption capabilities?

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..."

I now understand your intent in posting the study but that implies you agree with the findings and apply that to transmission fluid. Is there anything in the study that says the same is true of any transmission fluid?

I am not trying to talk anyone into changing their fluid and I don't like intimidation tactics either. If you consider me as one who attacks, what are you refencing as an attack?

Anyone asking about--to change on not to change, always hears both sides and I think you input as something to consider is well founded.

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.

Certainly there are some who have had transmission problem at even less than 30,000 miles but there is going to be a highest frequency cluster somewhere or you don't have a bell curve. I agree we don't know where that is but 100,000 miles is not a bad guess. I know you think most AT failures are due to complexity. I just don't understand how you can apply the findings of an oil study to ATF or the forum posts of non BMW mfg. or transmissions other than E53s as endorsement.

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.

I don't remember if any transmission posts reference that bad fluid was a cause- but I try not to retain a lot of things I can look up, My guess is fluid is seldom mentioned as it would be a symptom and not the cause of the problem and no one would ask if it was caused by the fluid.

One thing I do notice is there are very few posts about how many trouble free miles an E53 owner has on their X that change the fluid at any interval.
If we go by the current collective posts it is justified to take the position that changing fluid is of no benefit.

It would be beneficial if we could create a questionaire about transmission failures-what happened and when, including all the pertinent questions to move toward a more informed position. It would certainly help me as far as watching for particular symptoms or potential preventatives. Problem is, I don't think anyone could come up with anything considered objective to any majority.


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.

I think it is an open discussion. I considered there is no winner as a paraphrase for-- we can't draw a conclusion either way, sorry that was not clear.

FYI--BMW defines lifetime fluid is as -- for the usable life of the transmission.

. 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.

[JCL]

Dallas: I don't think you attacked at all. I was referencing this and many similar threads over the years.

Cheers

Jeff

[SlickGT1]

Damn. I gave up on these threads lol. Glad you still at it JCL. Makes for a good read when the boredom sets in.