Originally Posted by ayao
FWIW ... This is what Mike Miller suggests in his maintenance FAQ:
"All the BMW gearbox rebuilders I know use Red Line MTL exclusively, regardless of model year or gearbox. The general consensus is that MTL is the better lubricant.
However, Red Line D4ATF will require less shifter babying during cold operation. I use Red Line MTL in manual gearboxes except where I canít trust the driver to shift properly when the gearbox is cold, in which case I use Red Line D4 ATF."
I had the same experience, Redline MTL
wasn't awful just "gummier" when cold than stock stuff LT2 in my experience. I never tried ATF though. Only in E36 that already called for ATF and it was great there.
I still worry a bit because BMW made a special fluid for this gearbox and I think some more research should be done before swapping the fluid.
Of course if a fellow addict is willing to risk their tranny for the greater good, to find out which is better, I think that is cool, I just feel bad for Dan Parker and his mess and would hate to see another 1Mer with a transmission/warranty fiasco.