Lazy man's tranny fluid maintenance

[JCL]

Originally Posted by Max Gunner

What has changed about the transmissions or fluid in them that makes them not benefit from any fluid change at all versus the not-so-distant past when BMW recommended ATF changes as frequently as every 15,000 miles? MG

In very general terms, what has improved over the past decade is programming that provides firmer shifts (less resulting heat and clutch wear), better transmission cooling, and more experience on the part of BMW as to fluid breakdown over time. However, that is all a side issue. It isn't about whether the fluid is better if it is new, it is about whether new fluid will extend the life of the transmission. I don't think it will. Transmissions will fail for many reasons, but old fluid hasn't been shown to be one of them. You would probably be better served by replacing all the sensors inside the transmission than the fluid. Even better would be to take the money spent on fluid replacements, and put it in a future transmission replacement fund.