Without the rear differential, you wouldn't be able to put any power to the ground. Whether it has an open differential or a limited-slip, the condition of the components inside your BMW's rear differential directly affects how you can put the power down. Inside the differential is a ring and pinion gear set, and just like everything else involving gears, it needs a lubricating oil. Replacing this fluid is the best way to maintain your drivetrain.
We recommend only using the OE BMW G1 Hypoid gear fluid. You are welcome to try other gear fluids, preferably one with a 75W-90 GL4 rating, but using the OEM oil is the best way to ensure the differential's components are properly lubricated. Once you have your fluid of choice, the fluid change is a very straightforward process. You should have no trouble with this job, even with minimal experience, as long as you follow the steps below.
BMW models and years applicable:
This DIY applies to numerous BMWs extending further than just the F30. The DIY includes the 2-series, 3-series, and 4-series models.
How much will it cost to replace BMW F30 rear differential fluid?
All you need to complete the change is a new drain plug and a couple of bottles of fluid. According to BMW, although the drain/fill plug is metal, the Viton-style seal they use is a one-time-use. The new plug will run you just over $5.
BMW sells 500ml bottles of fluid, and the differential takes roughly 1-1.2L. The bottles are around $60 a piece, so you'll need at least two bottles to fill the diff. Altogether, budget around $200 for the job. The extra money is best put towards some brake clean or rags to clean the excess fluid that will spill out of the diff.
How long will it take to replace BMW F30 rear differential fluid?
Replacing the fluid shouldn't take you long at all. Once you remove the vibration dampener, you can directly access the fill/drain plug. Put aside half an hour to complete the job in your driveway.
Parts required to replace BMW F30 rear differential fluid:
Tools required to replace BMW F30 rear differential fluid:
- CTA Extraction Pump
- BMW Extractor Adapter
- E12 Socket
- 14mm Hex Bit Socket
- ½" Breaker Bar
- ½" Extension
- Torque Wrench
Steps required to replace BMW F30 rear differential fluid:
Step 1: Remove the vibration dampener
Jack the back of the car up and place it onto jack stands. Just behind the differential, BMW installed a rubber damper onto the bottom of the subframe to absorb some of the drivetrain's vibrations and harshness for a smoother ride. You need to remove this damper as it sits directly in the way of the differential's fill and drain plugs.
Use an E12 Torx socket to remove the dampener's mounting bolt from the subframe. Set the dampener aside while you replace the diff fluid.
Step 2: Replace the fluid
The drain/fill plug is the large hex plug on the diff's cover. Use a 14mm hex bit socket to remove the plug from the cover.
Next, attach the extractor adapter to the extraction syringe. The adapter will allow you to reach into the diff and pull all of the fluid out. Then, pull the oil out with the extractor.
Once you've removed as much of the old fluid as you can, start filling the diff with new fluid, you don't need the extractor to fill the differential, but you can use it if you'd like to. Use the syringe to fill the differential until fluid starts to leak out of the fill hole. Fluid coming out signifies that the oil is at its required level.
After that, thread in the new drain plug by hand to prevent cross-threading. Then, use the 14mm hex bit socket and torque wrench to torque the plug to 60Nm. Use brake clean and some rags to clean off the excess fluid from the differential.
Step 3: Refit the vibration dampener
Fit the vibration dampener into position and thread in its mounting bolt by hand to prevent cross-threading. Then, use an E12 socket to tighten the bolt.
Lastly, jack up the back of the car, remove the jack and lower the vehicle onto the ground.
BMW F30 Rear Differential Torque Specs:
- BMW Rear Differential Fill & Drain Plugs = 60Nm or 44.3 ft-lbs, of torque
Replacing the fluid is the best way to extend the life of your drivetrain components without spending an arm and a leg on new parts. If you're interested in more DIYs for your BMW, you can visit bmw.fcpeuro.com and subscribe to our YouTube channel.