Quote Originally Posted by genphreak View Post
Can it be that the wrong fluid was used?
no, the problem is the age of the material of that bakelite ring. Many E32 750 and E31 850 owners have the same problem. But no big problem, replacement is available even from aftermarket and remanufactured ones for less than $200.
ATE once sold the bakelite ring as well as the seals as single spare items, but no longer available, they now only sell cpl. reman ones.