Bimmerfest - BMW Forums - View Single Post - Automatic Transmission Fluid - Lifelong or NOT?
View Single Post
Old 07-23-2011, 12:21 PM
BMW1999M3FL BMW1999M3FL is offline
Registered User
Location: Florida
Join Date: Jul 2011
Posts: 3
Mein Auto: BMW'99M3Manual_S52ConvE36
Transmission Fluid Change

Just as many of you are wondering about changing Transmission Fluid or to better leave it alone, I've been researching this issue for some time now.

I am pleased to read many of these threads as they are very informative. Thanks to everyone for taking the time to help out others. My e36 is a manual (140,000 miles), and I have heard that it is easier to do the flush (perhaps there is no filter in mine being a manual?)

I've asked/consulted with over a dozen people/tech, and I got nearly a 50:50 reply (changed it ASAP:at this stage don't touch it, just top it if needed)

Of course I don't buy into "lifetime" being lifetime of the vehicle. I agree with the people on here saying it is a marketing maneuver etc. I am a scientist (chemist), and I know about oil composition, metal particles, catalysis, heat effects, etc. Someone posted the ppm content of the metals and it is obvious that after 70K miles, the chemistry of the fluid is different. However, the difference is remarkably modest considering the length of time/mileage the fluid has been through. So the term "lifetime" certainly testify to the chemical resilience of the fluid, but not to its being consistently the same throughout the "lifetime" of the vehicle. I bet you that if someone tests the fluid after 12K they would find out that it has progressed toward deterioration already, and clearly a change may not be necessary at that stage.

So I am with all of you on the issue of it NOT being a lifetime (unless lifetime is set at 50K or even 100K miles; considering that most of us are not the type to own the vehicle for 36K miles and swab it with a newer one, otherwise we probably would not bother posting/reading on here!) However, I am a bit concerned that since mine was never done, it is quite possible that flushing it all out with brand new fluid may actually cause some additional issues, aside from progressive wear possibly caused by not having changed the fluid this far. I bought 2L of MTF-LT2 from the dealer, and I am considering "baby-ing" the change gradually. Perhaps a comical coincidence, but the 50:50 response I got is tempting me to do just that! Change 50% of the fluid. Any comments on this? Or perhaps in slower steps (much like one would change water in a fish tank!) You do not want to change 90% of the water or else you may shock the fish. I know the transmission does not have cells, however, it has been "used to" that oil which gradually deteriorated to its current state, and perhaps it behooves making a "gradual revert" to cleaner fresher oil, rather than a sudden change. If I had a brand new transmission, I would have changed the fluid at least every 30-40K miles.

Sorry for the long thread, but I appreciate if anyone has an opinion on 1. Manual vs. Automatic, 2. gradual change 3. or other comments!

P.S. I am not sure how to refer to a different thread on this forum other than copying the link in here, but I thought I should make a reference to where I saw the helpful chemical analysis kindly posted by @csmeance.

Last edited by BMW1999M3FL; 07-23-2011 at 12:28 PM. Reason: additions
Reply With Quote