Ray,

The Service Manual for the transmission AW 50-42 1992 - was given to me two years ago. TP 4305201, 446 pages...pg 251, Oil Change:

"The Oil should be changed only in the following instances:

A) When the on-board diagonostic system has recorded that oil temperature is too high (DTC 2-3-5)

B) When the oil smells burnt, is discolored and DTC not set. For example due to hard and continuous operation of the transmission.

C) For cars in continuous taxi service and cars used to tow trailers for extended mileage, oil should be changed at 75,000km serice intervals.

Remove protective cover under engine

Remove drain plug and drain oil from the transmission.

Reinstall oil plug with a new seal

Torque nut to 40Nm (18 ft. lbs)

Reinstall splash guard.

Remove Battery

Remove Battery tray

Detach return hose on the control system cover.

Insert a plug into the connection on the cover. Install a transparent plastic hose on the oil return hose connection.

Place a container beneath the hose to catch the oil.

Temporarily replace battery tray and battery.

Set the parking brake and set the gear shift selector to position P. Add approximately 2 litres of oil.

Start the engine and allow it to idle.

Turn the the engine off when air bubbles start to become visible in the hose.

Remove battery and battery tray, Remove hose from connection.

Refit oil return hose to transmission cover, replace battery tray and battery.

Add approximately 2 litres of oil.

Apply parking brake.

Start engine and let it idle, move the gear selector through all positions, stopping in each position for 4-5 seconds.

Move the gear selector to position P with the engine running.

Wait 2 minutes, then check oil level.

Top up if necessary, The transmission holds 7.6 +/- 0.25 liters.

Turn off engine

Clear DTCs"