The water drain hoses for the slide/tilt sunroof are partially permanently integrated in the body and cannot be replaced individually.
These water drain hoses can only be completely replaced with extensive body repair work (e. g. after an accident).
An individual solution is required for damage that was not caused by an accident.
BMW X3 Service & Repair Manual > Driveline+Axles: General information on final drive oil
1.0 GENERAL INFORMATION ON FINAL DRIVE OIL
Final Drive oil or hypoid gear lubricant must conform with the following requirements because of the high
loads which occur on the profiles of the hypoid gear teeth:
Load carrying capacity.
Sufficient protection against seizure.
Good wear protec ...