Quote:
Originally Posted by DaanBMW
Which oils did you find better for your gearbox, and how was this determination done vs. RL and/or other oils ?
Just to clarify: Since BMW spec'ed the LT-03 for MT's - which is an ATF, and this Dex VI seem an ATF pretty darn close to LT-03, why would this not work in an MT ? (not that I plan to use it, but trying to understand your point).
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The box in my 318i carries a spec for ATF as the MTL. ATFs are inherently a compromise, given weak EP and AW adds. Many, many folks use redline MTL, as I did as well.
But the Redline lost shift quality (notchiness, 1st gear engagement, etc.) after about a year of use. It would be noticable in cold weather (as one would expect). I since moved to Amsoil MTF, which is a 5w-30 type (slightly heavier than ATF, like Redline MTL, for better protection), and the shift quality has stayed consistent, even with more driving the last few years, indefinitely.
As is known on the 318i LSD (slightly smaller than the E30 325 diffs), the bearings get noisy. Running a blend from Specialty Formulations has kept the diff quiet in a real, noticable way as compared to running Redline 75w-90 and w-140 lubes.
Is this scientific? Not really, but we are starting to see that Redline engine lubes are failing some oxidation and foaming tests, so the ester baestock may not be all it is sold to be in non-racing applications. Weve seen redline get chewed up and spat out in Audi RS4 applications and other DI applications. While shear stable, we also can see some nasty wear metal loads in RL lubes used in engines in non-racing apps. Engine isnt the same as diff, but I dont hold a ton of faith in their lubes for all applications at this point. Too many personal and testing clues.
Regarding Dex VI vs III and the fact that the BMW lube is an ATF, well, the reality is that GM specs either synchromesh or their Dex III fluid for MTs, not Dex VI. Dex VI has not been licensed for MT use, and while perhaps it will be adapted, it is a variation on standardizd Dexron III type ATF chemistry. Besides being a more shear stable base lube with a far lower viscosity, the add chemistry differs, and synchros arent necessarily the same as AT clutch packs. Id want to be VERY sure that there is compatible chemistry there...