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.
On a Porsche 996 model equipped with a Tiptronic (automatic) transmission, the transmission contains an integrated rear differential (aka “final drive”) that uses manual transmission gear oil. To save time and money, it is a good idea to change the differential oil and automatic transmission fluid at the same time. 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.
The 996.1 models with the 3.4L engines and Tiptronic transmissions do not have a drain plug for the rear differential. Instead, there is only a fill plug which you will have to use to drain and fill the rear differential. For an overview of the procedure, check out the above DIY from the YouTube channel, Gregg Balser. While the video does not cover a Porsche 996, the steps to drain and fill the differential are the same. Detailed steps, parts, and tools required can be found below.
- Mechanic’s Tool Set
- Metric Hex Bit Socket Set, 3mm to 10mm
- 3/8 Inch Drive Click Torque Wrench (10-80 ft.-lb.)
- K Tool International Low Profile Jack (3.33 Ton)
- ESCO 10499 Low Profile Flat Top Jack Stands (Pair) (4 required)
- Wheel Chocks
- Drain Pan Measuring Cup, 2 Liter
- Fluid Transfer Pump Kit
- Disposable Gloves
- Safety Glasses
Tiptronic rear differential fluid capacity: 0.9 liters
Differential fill plug (8mm hex bit): 22 ft-lbs
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 off the ground
- To give yourself enough clearance to work, safely raise your vehicle using a lift or jack and jack stands.
- ENSURE YOUR CAR IS LEVEL! This is essential to ensure the correct fluid level.
- NEVER rely on a jack to keep your car up; use jack stands to safely support your vehicle.
- Also be sure to use wheel chocks to prevent your car from rolling.
- To lift your vehicle on jack stands, check out this helpful video from CarFanatic.
- While it is for the Porsche 997, the procedure for the 996 is the same.
- Once your car is on jack stands, give your car a hard shove to make sure it is secure.
Step 3: Remove the rear differential fill plug
- Locate the rear differential, which is the big round housing located in front of the oil pan towards the front of the vehicle.
- Then locate the differential fill plug which is the driver’s side of the differential.
- Use an 8mm hex bit socket to remove the differential fill plug.
Step 4: Drain the rear differential oil
- Using a fluid transfer pump as shown in this video from BleeingJeep, stick the upper hose into the differential fill hole; be sure to push the hose down into the bottom of the differential as much as possible.
- Place the other hose on the fluid pump into a measuring container
- Pump as much differential oil out as possible.
- Make a note of the exact amount of differential oil you removed; it should be close to 0.9 liters.
Step 5: Fill the rear differential with new gear oil
- On your new bottle of gear oil, mark how much oil should be remaining in the bottle once you fill the rear differential with the same amount of oil you removed.
- Stick the top hose of the fluid transfer pump into the new bottle of gear oil and stick the bottom hose into the differential fill hole.
- The differential has baffles inside, so slowly pump the new gear oil into the rear differential until you’ve added the same amount of oil that you removed.
- Replace the crush washer on the fill plug with a new one (see parts section for crush washer assortment set).
- Re-install the fill plug and torque it to 22 ft-lbs using a torque wrench.
- Inspect everything to ensure there are no leaks.
Step 6: Lower your vehicle back on the ground
- Lower your vehicle back on the ground.
- Clean up your work area and put away your tools.
- Save the used oil in a container, so you can recycle it at your local auto parts store.
