In this tutorial, you will find instructions on how to change the front differential fluid on Mercedes-Benz 4Matic vehicles. Changing Mercedes front differential fluid is very easy and most DIYers will be able to complete this job in less than one hour. The pictures in this guide are taken from a differential fitted on 2006-2011 R Class W251, ML Class W164, and GL Class vehicles. While the front differential is slightly different in E, C, S-Class models these instructions can be used as a general guide for all owners of Mercedes-Benz with 4Matic.
Drive your Mercedes-Benz up on car ramps. Set the parking brakes. Place a block behind the rear wheels to prevent the car from rolling back.
Slide under the vehicle. Remove the front splash shield. It is held in place with several 8mm screws.
Locate the drain and fill plug. Note that some models only have a fill plug. The same plug is used for draining the oil. If your Mercedes differential only has one plug, use a transfer pump to suck the oil out of the front differential.
Always remove the fill plug first. The reasons why you need to remove the fill plug first is that the plug may strip or is rusted and you may not come out. If you drain the differential fluid
Next, remove the drain plug and allow the oil to drain. Pay attention of the color of the oil. If the oil has a silver look it may indicate that the bearings of the front differential are failing and will need to be replaced in the near future.
Once all fluid has drained from the front differential of your Mercedes-Benz, it is time to reinstall the drain plug. Replace the plug or the washer if a new drain plug is available.
Add Mercedes differential fluid until the differential is full and you see fluid starting to drip from the fill hole.
Reinstall the fill hole plug. Re-insert the filler plug at a torque of 30 ft/lb. Make sure you install a new copper washer.