Let's talk Transmission Maintenance...

[FSETH]

Originally Posted by ard

How can they talk out of both sides of their mouths?!?!

They say "100k" after the ridiculous lifetime recommendation...but still say we don't recommend it due to the 'increased risk': Which is it?

It is an easy answer: do it at 30-40k, just a gentle fluid change, and then you'll never risk loosening sludge or what not.

neil- with that many miles I'd be worried too. Do you think they will make it to 200k? With that original fluid? poor next owner

I'd love to get an oil analysis on that 9 year old ATF to see how well it protects.

Seems like most auto transmissions fail due to issues other than lack of fluid changes. I think auto transmissions are just flaky at best. That is why there have been plenty of people here with under 50,000 miles that have had transmission issues, regardless of fluid changes.

[JCL]

I just read this thread to refamiliarize myself with it. I stand by what I said previously, but I didn't ever mention the higher detergent content of the new fluid, not sure why. That high detergent level (by design, part of the fluid spec) tends to clean out the old crud, moving it. I think that is part of the reason for problems appearing after fluid changes of transmissions that were working fine prior to the change.

FSETH: Look at the tear down pictures in the threads on this site, and see the number of broken snap rings, and things of that nature. No way an oil change is going to help prevent those types of failure. I wouldn't use the word 'flaky', but I would use the words 'overly complex'. Complexity is the enemy of reliability. With respect to Mr Miller's recommendations, I don't understand how they can be called 'old school' while he is not recommending using an approved fluid. To me, old school is conservative and traditional, and that would include using recommended fluids if one did decide to change it.

ARD: You know that changing transmission fluid regularly (and early) may prevent problems of changing aged fluid (no crud to move, etc). But IMO you should also acknowledge that changing the fluid in that way does not ensure that a transmission will run 20 years (or however long the vehicle will last). Failures we are seeing posted do not appear to be related to fluid breakdown. Your point on understanding cause and effect. So while an early and unscheduled fluid change is intuitively a good thing, it is like buying a lottery ticket; it may pay off, but it probably won't. That goes back to the point in that article I posted earlier in this thread, that transmission failures are not necessarily more likely as the transmission ages. The random nature of the failures we have seen supports that. Also, if you could test transmission fluid, what would you test for? How would you quantify the state of the friction modifiers? And finally, how can you call a lifetime fluid recommendation ridiculous without any data on transmission failures and respective causes?

Cheers

Jeff

[diesaroo]

Originally Posted by JCL

I just read this thread to refamiliarize myself with it. I stand by what I said previously, but I didn't ever mention the higher detergent content of the new fluid, not sure why. That high detergent level (by design, part of the fluid spec) tends to clean out the old crud, moving it. I think that is part of the reason for problems appearing after fluid changes of transmissions that were working fine prior to the change.

FSETH: Look at the tear down pictures in the threads on this site, and see the number of broken snap rings, and things of that nature. No way an oil change is going to help prevent those types of failure. I wouldn't use the word 'flaky', but I would use the words 'overly complex'. Complexity is the enemy of reliability. With respect to Mr Miller's recommendations, I don't understand how they can be called 'old school' while he is not recommending using an approved fluid. To me, old school is conservative and traditional, and that would include using recommended fluids if one did decide to change it.

ARD: You know that changing transmission fluid regularly (and early) may prevent problems of changing aged fluid (no crud to move, etc). But IMO you should also acknowledge that changing the fluid in that way does not ensure that a transmission will run 20 years (or however long the vehicle will last). Failures we are seeing posted do not appear to be related to fluid breakdown. Your point on understanding cause and effect. So while an early and unscheduled fluid change is intuitively a good thing, it is like buying a lottery ticket; it may pay off, but it probably won't. That goes back to the point in that article I posted earlier in this thread, that transmission failures are not necessarily more likely as the transmission ages. The random nature of the failures we have seen supports that. Also, if you could test transmission fluid, what would you test for? How would you quantify the state of the friction modifiers? And finally, how can you call a lifetime fluid recommendation ridiculous without any data on transmission failures and respective causes?

Cheers

Jeff

Are you referring to what happened to swissfrank with the snap ring failure? This by his own admission was caused by abuse in deep snow.

I think eveyone is still forgetting about the filter. New fluid is better, but even if the old fluid is still good enough at high mileages, the original filter will not be doing any good after 60-100k miles. I suspect that it will be in full bypass mode by that time.

Old fluid or new fluid, without a properly functioning filter, unmitigated wear metals and clutch material is circulating through the transmission causing accelerated wear leading to failure.

[JCL]

Originally Posted by diesaroo

Are you referring to what happened to swissfrank with the snap ring failure? This by his own admission was caused by abuse in deep snow.

I think eveyone is still forgetting about the filter. New fluid is better, but even if the old fluid is still good enough at high mileages, the original filter will not be doing any good after 60-100k miles. I suspect that it will be in full bypass mode by that time.

Old fluid or new fluid, without a properly functioning filter, unmitigated wear metals and clutch material is circulating through the transmission causing accelerated wear leading to failure.

I was referring to many documented failures, swissfranks being only one of them. While some are snap rings, others are temperature sensors, wiring, actuators, or broken metal pieces that are static, ie not dependent on lubrication. What these failures have in common is a lack of connection to fluid condition. One could make a case that the various o-ring failures are related to the fluid condition, but it would be only a guess.

I hear your point on the filter, but do you have data that suggests that clogged filters are causing transmission failures? I equate fluid failures with burnt clutch plates, and clogged filters with low fluid pressure, again often appearing along with burnt clutches and evidence of overheating. The overheating failures we have seen documented have been linked to mechanical failures that resulted in overheating, ie the burnt components were a result, and not a root cause.

[Penguin]

Originally Posted by ICX5

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).

Having worked as a Product Planner at an Automotive manufacturer many, many years ago, I can tell you that Marketing believes long service intervals are a competitive advantage, as the typical customer finds service to be an inconvenience at best, and an irritating hassle at worst. I have been in meetings where Marketing was arguing with Engineering to lengthen the engine oil change interval to be longer than competitors.

A vehicle which needs no service at all is Marketing's dream, and they really do think it would be an important selling point and result in significant incremental sales.

[diesaroo]

Originally Posted by JCL

I was referring to many documented failures, swissfranks being only one of them. While some are snap rings, others are temperature sensors, wiring, actuators, or broken metal pieces that are static, ie not dependent on lubrication. What these failures have in common is a lack of connection to fluid condition. One could make a case that the various o-ring failures are related to the fluid condition, but it would be only a guess.

I hear your point on the filter, but do you have data that suggests that clogged filters are causing transmission failures? I equate fluid failures with burnt clutch plates, and clogged filters with low fluid pressure, again often appearing along with burnt clutches and evidence of overheating. The overheating failures we have seen documented have been linked to mechanical failures that resulted in overheating, ie the burnt components were a result, and not a root cause.

I think most people will replace a transmission or sell the car if it slips regularly even if it still does shift eventually because it no longer meets their perceived needs.

I had an '89 Chevrolet Celebrity SW that I bought used and the PO had done some partial replacement of the fluid 60-70k miles prior to my ownership, but the filter was never replaced. I eventually sold it at 167k miles due to very rough shifting, believing the tranny was about to go out. The guy I sold it to several years ago still drives on the same tranny, rough shifting and all.

The level of operation did not meet my standards, but to him, it still drove and he was content with that (I sold it to him for scrap value).

I have a '00 Subaru Outback SW that I bought used with 42k miles on it. It now has 135k on it on the original transmission. I changed the transmission fluid on it at 55k, 88k, and 115k. I did not change the filter until 115k because I followed the recommendation from subaru that the filter is "lifetime". Until I changed the filter, there were metal particles on the dipstick (yes it does have an AT dipstick) and in the fluid along with somewhat rough shifting. I may have "gottn away" with not changing the filter due to my frequent fluid changes that got the metal and clutch material out reguarly. I cut open the old filter and it was full and choked with PM. After that experience, to me "lifetime" means as long as they want you to own it for so that they can sell you a new car!

To me it makes sense that unfiltered particulate matter of all sizes being constantly recirculated into all the inner workings will either cause serious operating problems or may contribute to a CTF.

Also, I don't think AT filters are analogous to fuel filters, but are more like oil filters in that once the flow restriction is too high due to cold weather or clogging, the filtration is bypassed and line pressure is maintained.

[diesaroo]

Originally Posted by JCL

I was referring to many documented failures, swissfranks being only one of them. While some are snap rings, others are temperature sensors, wiring, actuators, or broken metal pieces that are static, ie not dependent on lubrication. What these failures have in common is a lack of connection to fluid condition. One could make a case that the various o-ring failures are related to the fluid condition, but it would be only a guess.

I hear your point on the filter, but do you have data that suggests that clogged filters are causing transmission failures? I equate fluid failures with burnt clutch plates, and clogged filters with low fluid pressure, again often appearing along with burnt clutches and evidence of overheating. The overheating failures we have seen documented have been linked to mechanical failures that resulted in overheating, ie the burnt components were a result, and not a root cause.

I do agree with you however that there will always be cases of transmission failure that are the result of a bad internal parts failing unrelated to fluid condition, although I would tend to believe that they would show up earlier in the vehicles service life than later on and would be likely during the warranty period.

This can and does happen unfortunately with any type of part on the vehicle. There have been at least one case of catastrophic engine failure in the M57 due to the injector going haywire (sensor) and washing down the cylinder walls causing the piston to seize in its bore. Does this mean that I should change my engine oil at the prescribed 11k mile intervals instead of 5500 miles? BMW says its ok, so why not? I mean if it might grenade on me anyway due to the injector sensor, why spend extra money on it?

I personally just can't seem to enjoy car ownership if I adopt a defeatist attitude and allow the car to degrade and wear out by following a bare bones-I-will-if-I-have-to maintenance schedule. I am not trying to offend you, but whatever happened to taking pride in your machine?

[JCL]

Originally Posted by diesaroo

To me it makes sense that unfiltered particulate matter of all sizes being constantly recirculated into all the inner workings will either cause serious operating problems or may contribute to a CTF.

Also, I don't think AT filters are analogous to fuel filters, but are more like oil filters in that once the flow restriction is too high due to cold weather or clogging, the filtration is bypassed and line pressure is maintained.

I agree that unfiltered particulates will over time cause wear. More so metallic particles than clutch material, but yes. The question is whether reducing that wear will extend the life of the transmission. If the wear is so slow that the transmission is likely to fail for completely different reasons before the wear becomes critical, there is little point in reducing the wear.

As the transmission filter is essentially a screen over the oil pickup, how does the bypass work?

[JCL]

Originally Posted by diesaroo

I do agree with you however that there will always be cases of transmission failure that are the result of a bad internal parts failing unrelated to fluid condition, although I would tend to believe that they would show up earlier in the vehicles service life than later on and would be likely during the warranty period.

See my post #29 in this thread. I provided an article on paradigms of maintenance, which discusses whether failures in complex systems are more likely to occur with time, or not. My point is that the transmission failures most will see are not in fact wear out, but are due to random mechanical and electrical failures.

Originally Posted by diesaroo

I personally just can't seem to enjoy car ownership if I adopt a defeatist attitude and allow the car to degrade and wear out by following a bare bones-I-will-if-I-have-to maintenance schedule. I am not trying to offend you, but whatever happened to taking pride in your machine?

I am not offended, but you don't know me, and you are prescribing opinions to me that are incorrect. I am a car nut. I like working on my own vehicles, for the pleasure of doing the work as much as for the outcomes. I am not at all defeatist. There is nothing bare-bones about my personal maintenance strategies. While I take pride in my vehicles, I just don't see the logic in taking pride in having changed a fluid that didn't need changing, thereby introducing potential contamination to a sealed system, and raising the chances of infant mortality post-change. Maintenance is a science, not a black art, or act of faith, IMO. Recommend again that you look at the attachment in my post #29.


Jeff

[ard]

Originally Posted by JCL

I agree that unfiltered particulates will over time cause wear. More so metallic particles than clutch material, but yes. The question is whether reducing that wear will extend the life of the transmission. If the wear is so slow that the transmission is likely to fail for completely different reasons before the wear becomes critical, there is little point in reducing the wear.

Statistically speaking, if I owned 1000 transmissions, your strategy might be best. A science if you will.

It seems you've already determined that the wear is,in fact, low- and that the tranny will most likely fail for something other than sludge, particular wear, or lack of lubrication.

But on the off chance that my tranny will not fail for one of the other things you cite, I'll freshen the ATF. Statistically speaking for MY ONE TRANNY it is a superior maintenance strategy.

This is, in fact, an "oil thread" in that nobody has the real answer- all we have are BS marketing materials from BMW and Getrag, and our beliefs.

I propose a two prong plan:
1. Run Used Oil Analsys (UOAs) on virgin ATF, then at 20k, 40k, etc. Compare.

2. Buddy up to a Getrag engineer at Octoberfest, get them to spill their guts.

A