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."