Changing your rear differential oil is important to keep your drivetrain smooth. Over time, the oil loses its critical properties that prevent metal on metal contact. This is a easy do-it-yourself as long as you have the proper tools and ability to get your vehicle off the ground safely. If you are unsure of how to do this procedure, please visit a certified mechanic.
While Porsche recommends owners change the differential fluid every 16 years or 160,000 miles, we believe this is too long. This is a cheap and easy do-it-yourself as long as you have the proper tools and ability to get your vehicle off the ground safely. For an overview of the procedure, check out the above DIY from the YouTube channel, DIY Dan. While the video covers a 955/957 generation Cayenne, the procedure is nearly identical on the 958 Cayenne. Detailed steps, parts, and tools required can be found below.
- Mechanic’s Tool Set
- K Tool International Low Profile Jack (3.33 Ton)
- ESCO 10498 Performance Jack Stands (Pair) (4 jack stands required)
- Wheel Chocks
- 3/8 Inch Drive Click Torque Wrench (10-80 ft.-lb.)
- Stubby Allen Key Set
- Metric Hex Bit Socket Set, 3mm to 10mm
- Fluid Transfer Pump Kit
- Oil Drain Pan, 6 Quarts Capacity
- Safety Glasses
- Disposable Gloves
- Motul Gear 300 75W-90 Oil, 1 Liter - P/N: 105777 (for vehicles with standard open rear differential, 1 liter required)
- Motul 75w90 Gear Oil, Limited Slip - P/N: 105778 (for vehicles with locking rear differential option, 2 liters required)
- Differential Drain/Fill Plug - P/N: 95533205700 (2 required)
Differential drain and fill plugs: 26 ft-lbs
Oil capacity (non-locking differential): 0.8 liters, fill until oil is 3mm (+/- 2mm) below bottom edge of fill port
Oil capacity (locking rear differential option): 1.3 liters, fill until oil drips out of fill port
Step 1: Prepare your vehicle and work area.
- Starting with a cold engine, drive your car lightly for 5 minutes to get the drivetrain fluid warmed up; this will make it easier to drain the differential fluid.
- Park your car on a flat surface.
- Gather required tools and parts.
- Put on gloves and eye protection.
Step 2: Raise your vehicle to give yourself extra clearance.
- If you have air suspension, simply raise your car to the highest ride height.
- If not, raise your vehicle with a lift or jack stands; it is very important your car is level during the procedure.
- Be sure to use wheel chocks and the parking brake to prevent your car from rolling.
- To get jack stands on the front jack points, jack the vehicle by the center cross member as shown in the photos.
- To get jack stands on the rear jack points, jack the vehicle up be the rear cross member which is just ahead of the rear differential and in between the exhaust pipes.
- NEVER rely on a jack to support your vehicle.
- Note: If you have air suspension and decided to jack up the car, you will need to lock the air suspension by starting the car and holding the air suspension button up for 10 seconds. You will see an indicator pop up on your gauge cluster.
Step 3: Remove the rear differential fill bolt.
- Crawl under the rear of the vehicle and locate the rear differential.
- As shown in the video from TOM RAST, you should see two 8mm hex bolts. The one on the bottom is the drain bolt. The one located higher is the fill bolt.
- Remove the fill bolt with a stubby 8mm allen key (linked in tools section).
- If you cannot get the fill bolt off, STOP and do not proceed with the procedure.
Step 4: Drain the rear differential.
- Place a drain pan under the drain plug.
- Remove the drain plug using an 8mm hex bit or allen key.
- Allow the differential to drain for 15 minutes.
Step 5: Fill the rear differential with fresh oil.
- Install a new drain bolt and torque it to 26 ft-lbs; if reusing your old one, make sure it is in good condition before reusing.
- Add ~0.9 liters of oil to the differential via the fill port using a fluid pump as shown in this video from BleeinJeep; you will top off the oil in the next step.
Step 6: Check oil level and top off if necessary
- If your vehicle is equipped with the rear locking differential option, simply add oil until it begins to drip out of the fill hole.
- If your vehicle is equipped with the standard, non-locking rear differential, you will need to use a paper clip bent in an L-shape or small allen key to check the oil level.
- The oil level is measured from the lower edge of the fill port to the top of the oil level; insert the L-shape paper clip or allen key into the fill port and use it as a dip stick.
- The distance from the lower edge of the fill port to the top of the oil should measure 3mm (+/- 2mm tolerance).
- If needed, add more oil until the right level is reached.
- Install the fill bolt and torque it to 26 ft-lbs.
- Note: We recommend you install new drain and fill bolts; however, if you do not have new ones, make sure your old drain and fill bolts are in good condition before re-using it.
Step 7: Lower your vehicle.
- Lower your car.
- Store the old gear oil in a plastic container, so you can take it to your nearest auto parts store to recycle.
- Clean up your workspace and put all of your tools and supplies away.
- You’re all done!
