Change the oil in the gearbox housing every 30,000 km immediately after the trip:
- unscrew the drain plug and, to speed up the draining of the oil, the filler plug;
- on BMW «525», «528» both plugs are located on the right side of the gearbox housing, on «520i» - From the left side.
Plugs have a tapered thread for tightness. Tighten the plugs to the required torque.