- 01/25/2017
- 0 Min Read
- By: Alex Fiehl
How to Change Rear Differential Fluid on a BMW (RWD, AWD)
Similar to a transmission fluid change, regularly changing the fluid in the rear differential will help prolong its life. This is not an expensive or time consuming task, so frequent changes can't hurt. If you are driving in a manner that is hard on the drivetrain, more frequent is recommended.
What You Need
- Drain Pan
- 2 quarts of recommended gear oil
- Siphon pump 12-16mm hex socket set
- Paper towels
- Safety glasses
- Rubber gloves (gear oil smells terrible you do not want it to stick with you)
Before you start, go for a 25-30 minute drive to get the fluid warmed up. This will aid in the draining and will help any loose particles to also come out.
Once you get home, get the car on jackstands, ensuring the car is level and secure. On the differential there are two hex plugs. Remove the top one first, this is the fill plug. The reason you want to remove the fill plug first is if you cannot remove it for some reason, you do not want to drain the fluid and not be able to put new fluid in.
After you remove the fill plug successfully you can remove your drain plug, making sure the drain pan is in a good spot to collect the fluid. Gear oil smells pretty bad so you don’t want that smell to linger. Let it drain for quite a while (gear oil is much thicker than regular oil). Once it's completely drained, use paper towels to clean the threads for the plugs, and put the drain plug back in and tighten to about 33ft-lbs (37ft lbs max). Use a siphon pump to put the new fluid in, stopping when the fluid starts to dribble out of the fill plug. Put the fill plug in and tighten to 33ft-lbs.
