Drive line fluid change
 

I changed the fluids in the front and rear differentials and the trans axle today at 88K miles. It was an easy enough procedure, the most difficult operation was removing the front skid plate. I also needed to buy a 14mm hex drive to open the plugs on the differentials. Once drained I replaced the differentials with about a quart each with Red Line 75-90 gear oil, and the trans axle with another quart of BMW part # 83 22 0 397 244. The discarded fluids were dark brown but showed no signs of metal shavings.

nice i did all of them not long ago, rear diff stinks lol
you can use any ATF Dex III in the transfer case btw