Changing Porsche 928 S4 Differential Gasket and Fluid
I recently took on the task of replacing my 1989 Porsche 928 S4 differential gasket and fluid. When you look at videos online the Porsche 928 S4 has a different size Allen Key than the non S4. Here are the general steps I used, this is to aid with the manual:
- Buy AMSOIL Severe Gear 75W 90 4 Quarts (you will have some left over)
- Buy the pump (its only a couple dollars)
- Buy new crush rings, its the cheapest Porsche part I have ever bought. Less than $1.25 at the dealer.
- Evenly raise car in the air and put on stands. Never get under the car without stands.
- Clean the differential for several hours. You don’t want any grime inside your differential.
- Place oil pan under car.
- Open the fill plug and take off. If you cannot remove this do no proceed without an experts help.
- Open the drain plug and lets all the oil fluid drain.
- If you only want to change the fluid simply put the drain plug back in and torque to the manual specs. Then fill up using the pump. I don’t think its possible to not use a pump because of the location of the fill hole. Make sure you pump some gear oil on the threads of the drain and fill plugs to they don’t get corroded. Also torque to the specs in the manual.
- If you want to take off the cover to replace the gasket you need to drain the fluid.
- Loosen the exhaust clamps so you can move the exhaust piped out of the way.
- Remove heat shield off of the differential using the special tool, I took a picture of it.
- Remove the differential cover
- Replace gasket, put back on drain plug, fill up, and put back on fill plug.