1. Raise the car on a lift or place it over an inspection pit.
2. On vehicles equipped with the BE3 gearbox, remove the left front wheel, unscrew the screws and remove the wheel arch guard from under the wing to access the oil filler plug. On all models, remove the splash guard from under the engine.
3. Clean the area around the oil fill plug. On the BE3 transmission, the oil fill plug is the largest bolt of the end cover bolts that attach to the transmission. On the ML5T transmission, the oil fill plug is located on the rear of the differential housing. Remove the oil fill plug from the transmission.
4. Place a suitable container under the oil drain plug located at the rear of the transmission and unscrew the plug.
5. Drain the transmission oil completely. Clean the oil filler plug and drain plug from metal particles and replace the sealing washers.
[Source available here: peugeotbook]
6. Screw in the oil drain plug and tighten it to the specified torque.
7. Fill the gearbox with oil to the level of the lower edge of the oil filler hole.
Attention! For correct filling of the gearbox the car must be in a horizontal position.
8. Replace the oil filler cap, install the wheel and take a short drive. Recheck the oil level.
9. If necessary, adjust the oil level, install a new sealing washer on the plug, screw the plug back in place and tighten to the specified torque. Install the wheel arch protection and engine splash guard.