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Discussion Starter #1
Has anyone done their differential oil changes yet? If so do you have any words of wisdom on how to change the fluids and what gasket/crush washers will need to be replaced.
 

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At what mileage/under what conditions is it recommended to replace the differential oil?
My next concern is the 30k service to inspect the CVT and differential oil. Honestly I don’t trust a dealer to do anything more than look at it and call it good, which I really don’t feel like paying for, but I don’t know anything about doing that part of the service myself...
 

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There's some good discussion/info on this in the following thread:

 

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Recommended is "Inspect every 30,000 miles".

One must make sure that they unscrew the right fill bolt for the front differential (the drain bolt is labeled). The wrong one goes into the CVT.

Check https://parts.subaru.com/ for the latest part numbers, as these do change quite a bit.
 

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Discussion Starter #5
At what mileage/under what conditions is it recommended to replace the differential oil?
My next concern is the 30k service to inspect the CVT and differential oil. Honestly I don’t trust a dealer to do anything more than look at it and call it good, which I really don’t feel like paying for, but I don’t know anything about doing that part of the service myself...
According to the service schedule the diff fluid is good for a lifetime unless it sees severe service then it is only good for 15k. Other Subaru’s recommended changing the diffs at 30k. Since I am past the 30k and plan to put lots if miles on my Ascent and gear oil is cheap I thought it would be good to change it out. I am hoping that someone is ahead of me on this one or read the service manual and can tell me how it’s done. Should be fairly straight forward but this is my first Subaru and I want to make sure that there are not any unusual steps to the procedure like on the CVT.
 

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^^ I’m all for it. As I stated I doubt the dealer will actually do a meaningful inspection so if changing it won’t hurt it let’s git r done
 

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I changed mine at about 28,000 miles.
 

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Did you do one of your “how to“ videos on the diff fluid change?
No, I had someone else do the work. I just showed them the fill plug on the front.
 

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Use same 75w-90 gear oil. Subaru or equivalent. I started with Subaru, but had to change front diff a second time when I found the drain plug washer in the bottom of my drain pan after refilling.
 

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The car should be leveled for accurate filled measurement (i.e. fluid topped to bottom of fill hole). The typical problem is always access and using your muscle to leverage the awkward positions.
 

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Discussion Starter #16 (Edited)
Pulled the drain plug and drained the gear oil. After putting the drain plug back. The diff is refilled through the vent port. The vent is easily removed just by pulling on it.
3409
3410
 

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Discussion Starter #18
The only issue I had was the parts guy at the dealer for some reason assumed the drain and fill plugs front and rear all had the same size gaskets. So I had four new gaskets that only fit the rear drain and fill plugs. The front gaskets were in good shape and I reused them. New gaskets for the front are on order.
 

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I'll be doing both diff fluid changes myself as well in the near future. How much replacement fluid is needed for each diff? I normally use Mobile 1 or Royal Purple - does that work well for Subarus (this is my first Subaru).
 

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I'll be doing both diff fluid changes myself as well in the near future. How much replacement fluid is needed for each diff? I normally use Mobile 1 or Royal Purple - does that work well for Subarus (this is my first Subaru).
1.3qt and 0.8qt front and rear, respectively. Here’s what the manual says about the type of oil to use:
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