This is the only 4-wheel drive available from BMW. The transfer case contains 1.1 pts. (0.6l)®II or III ATF. This is the factory recommended fluid to use in the transfer case.
Remove the filler plug on the side of the transfer case. The fluid should be level with the bottom of the filler plug hole. Torque the plug to 22-25 ft. lbs. (30-35 Nm).
DRAIN AND REFILL
The transfer case has a drain plug that is removed to drain the fluid. To fill the transfer case, open the filler plug located on the top edge of the case and add the fluid. The fluid should flow from the filler hole, this is how you know it is full.