Maintenance: Subaru Rear Diff Oil Change

All this talk about converting to RWD reminded me that I haven’t changed the oil in the rear diff yet. I didn’t know if it had ever been changed and after installing the SuperPro Outrigger Bushings, there was a little hum coming from the rear.

I had a short trip planned so I decided to go ahead and change the rear diff oil.

As with any diff or transmission with a fill plug, we want to remove it first before removing the drain plug.

The plugs were on pretty tight so I used an impact to remove them. Thankfully, there were no metal chunks on the drain plug magnet. And the oil looked pretty clean as well.

For oil, we are using Subaru High Performance 75w90 gear oil that I had left over from the transmission rebuild. The R160 only takes a quart but one bottle was open already.

After the oil drained, we can put the drain plug back in and fill it up with gear oil. This fluid pump makes things a lot easier.

We fill the diff until oil runs out of the fill plug and then button everything back up.

For my trip, I took the car through the Tail of the Dragon (more on that in another post), and I didn’t hear the whining sound from the rear end. The car did seem a bit smoother but it’s hard to say for certain. Either way, this was a maintenance item off the list and we can move one step closer to RWD glory.



  1. Peter Spinale says:

    I’ve used “scotty’s cocktail” in the wrx, it has kept it quiet the last 10k miles. If you ever rebuild one I will suggest genuine Subaru axle seals. Mine leaked until I went with OEM.

    Liked by 1 person

    1. A.A.Smith says:

      I’ve never had good luck with aftermarket gaskets and seals on a Subaru. Except for GS exhaust gaskets.

      That said, I did buy an aftermarket o-ring kit to fix a couple of oil leaks on the engine. But I am reserving judgement for at least couple thousand miles.


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