This part is freely translated form the Dutch manual “Mercedes-Benz L 613 D (1977) Truck”
The manual “Mercedes-Benz L 613 D (1977) Truck” states:
4.8.3 Checking the oil level and oil change
Mechanical steering wheel
Check the oil level regularly. It
oil level must be up to the bottom edge of the filler opening. Clean the steering box in the area of the flap plug before loosening it. An oil change is not necessary.
Servo steering
The oil level in the oil reservoir of the servo steering wheel must be checked regularly. The oil level must be up to the mark in the reservoir.
Change oil:
Jack up the front axle. Unscrew the flap plug from the steering box. The engine for a short time, max. Run for 10 seconds until the oil has been sucked out of the pump and reservoir.
After turning off the engine, turn the steering wheel again completely from one stop to the other for a check, until no more oil flows out.
Then install the oil drain plug and the new filter element and fill the reservoir with oil up to the mark.
Press the engine sail button. Run the engine for a short time with the starter motor and gradually add oil. Then let the engine idle and turn the steering wheel vigorously from one stop to the other. This automatically bleeds the servo steering.
Let the engine run until there are no more air bubbles in the oil reservoir. Place the lid on the reservoir and tighten it. Check whether the ring closes properly.
