Necessary preliminary work:
Pull temperature sensor (1) out of retaining lug (2).
Installation note: Make sure rubber ring is correctly seated.
Disconnect plug connection (1) and remove temperature sensor (2).
BMW X3 Service & Repair Manual > Front axle gearbox: Removing and installing/replacing front axle differential
IMPORTANT:
For the initial filling of a new replacement front axle differential, the gearbox is filled with 600
ml oil! If oil is filled up to the lower edge of the oil filler opening, the gearbox would be
overfilled and in rare individual cases oil could emerge from the ventilation opening ...