Originally Posted by Tom K.
I appreciate your reasoning and will be deciding on a fluid next year for my E91 and 128i. MTL worked very well on my E46 5 speed, but why do you think Red Line recommends D6 for the E90, rather than MTL?
My E90 came with MTF-LT2 according to the sticker on the transmission. I know that later ones seemed to come with MTF-LT3 from the factory.
MTF-LT3 is thin, and D6 ATF is the closest match in that regard. Notice that the transmission didn't change when the sticker changed - it's still the same as when the E90 was launched.
I spoke/emailed with Dave @ Redline once about MT fluid recommendations and he basically told me that they spec ATF because it's the thinnest and they don't want any BMW owners from Alaska complaining (possibly publicly) that Redline caused hard shifting. He told me that MTL and MT90 would also be perfectly fine to use in my E39 but that I *might* have some shift feel degradation depending on how cold it gets where I am.
So, all that being said, I like MT-dedicated fluids the best and have run MTL through Toronto winters for years with no problems whatsoever. Ditto for Amsoil MTF.