Newly BMWs have lifetime transmission and differential fluids that do not need to be changed during the lifetime of the BMW. Dealers even warn you that changing it may do more harm than good.

Now many BMW owners do not believe this and continue to maintain their bimmers according to the older BMW maintenance schedule. Even bimmer magazine recommends that those fluids be changed because they see transmission or differential probblems on 100K and above cars.

My question to these claims is: how do you know the failures are caused by not changing fluids?

Some contend that BMW do this becaure they do not care about maintenance. they are in teh business of selling cars, implying that BMW want your car to break down at about 100K so you can buy new cars from them again. My question again is this: do you think BMW will risk their reputation to intentionally let BMW cars to fail pre-maturely by not changing fluids? If this is so, why do they not recommend lifetime engine oil?

I think before BMW makes this recommendations, they must have done an extensive research which the recommendations are base on.

Lifetime means lifetime, meaning as long as you still drive you car, not changing transmission/differential fluids will not be the reason when those parts do fail.