Hi i am about to do service on my recently purchased 94 E36 M3, does anyone have any advice about which oils makes and weights are best for engine gearbox and Dif on these cars? Is it best to stick with genuine BMW for diff oil etc? So far i have been advised to put three different weights of oil in the engine! (5-40, 10-40 and 10-60). Obviously i don't want to put an oil in that will just "do the job".