The purpose of transmission fluid is to lubricate all parts of the transmission and act as a coolant. Older Mercedes models had dipsticks that allowed the driver to check the transmission fluid. In the late 1990s, Mercedes stopped including a transmission fluid dipstick in its vehicles. Only Mercedes mechanics can access the transmission fluid. In newer models, Mercedes says there is no need to change the transmission fluid over the lifetime of the car.
Drive your Mercedes until it is warm. Transmission fluid should be checked after the car has been running.
Open the bonnet. The bonnet release is located near the driver's side door. If you have an older Mercedes, open the bonnet by pulling on the tab that protrudes from the grill while lifting up on the bonnet.
Locate the transmission fluid dipstick. It's near the passenger's side in the rear of the engine compartment.
Pull the dipstick out and wipe the end with a clean, lint-free towel. Insert the dipstick fully back into the tube, then pull it out again. Look at the end of the dipstick to see the level of transmission fluid in relation to the maximum fill level mark. Take note of the colour of the transmission fluid. Transmission fluid that is a muddy colour should be changed. Fresh transmission fluid is a translucent red.