As part of a major refresh I just did, I just did the transmission detents and replaced the fluid with valvoline MTF (supposedly a suitable mtf lt-1 subsitute).

I had notchiness (or slight grinding if I shifted too fast) going from 1st to 2nd gear that I always thought was a worn synchro. The X5 exhibited this behavior since I got it at 100k miles, but now it absolutely feels like a new transmission! Don't know if was the fluid or the detents, but I'm guessing both as I had the 5th gear 'lean' and sort of had to hunt for the gates a bit.

__________________
2012 xDrive35d
2001 BMW X5 3.0i 5MT
and two 1987 Corvettes - Callaway Twin Turbo and Guldstrand Grand Sport 80
Block Tester