Modification to fluid change guidelines
 

There's a thread on the homepage, which covers the fluid maintenance schedule. Following issues and research i've had to do in the last 2 days on the topic, the front and rear diffs of the Xdrive models call for Castrol XAF-XJ which is a 75w-140 weight oil with LSD additives. The Xdrive models are limited slip whereas the non-Xdrive models are not. The Castrol fluid from the dealer runs about $40/liter. Any equivalent 75w-140 fluid with LSD additives such as RedLine or Royal Purple should do the trick as well.

My issue that brought me to these findings was a leaky front shaft seal. I put the wrong fluid [75w-90] during a recent service. Two days later the lower visosity fluid made its way out past the seals even faster than the 140 weight would have, ran down really low and I fried my diff. Granted that is no one's fault but my own, I just thought our readers and Xdrive model owners should be made aware.