2017 Subaru Outback Differential service

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I’m getting to do a differential service which gear oil should I go with Valvoline high-performance or or Valvoline synpower. Both are 75w-90 GL-5. Going to both the front and rear. Plan is do the. Once a year drive about 15-17k a year
 
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That's real conservative. Yeah they're good to use. What about your trans and transfer case.
 

JTK

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I think the main thing is the fact you're changing the gear oil. I used Supertech synthetic 75w90 in the rears of my Subarus. I never did do the front diffs on my 2012 Legacy CVT or 2016 Forester CVT because access to the fill plug was a pain without a lift. My 2014 Crosstrek was a 5MT, so the front diff shared the same gear oil as the gearbox.
 
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I’m getting to do a differential service which gear oil should I go with Valvoline high-performance or or Valvoline synpower. Both are 75w-90 GL-5. Going to both the front and rear. Plan is do the. Once a year drive about 15-17k a year

The service is recommended every 60,000 miles conservatively. Is there any reason why you want to do it or think that you need to do it at such a lower interval?
 
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I changed the diff & tranny oil in my '04 Forester back when it had 40k miles. The OEM oil came out black "well used" with some metal particles from the original breakin. I used Mobil 1 gear oil that met the spec (it was 10-15 years ago, may have been GL-4). Manual tranny so the front was diff+tranny and back was diff only, same oil. During the 100k mile service (timing belt, pulleys, water pump, etc.) I checked it and it still looked brand new. Not black or even dark. no reduction in level, no sign of water, contamination or wear. So that oil is still in there.

IME, after you change the diff/tranny oil after a few thousand miles of break-in, it may be good for life. Depending on the car & how you drive it.
 
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17 OB Limited here. I did my front/rear diffs at 25kish and soon will be at 125k and I'll do them again. I used Amsoil first but the next change will be Chevron synthetic 75/90 front and rear.
 
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17 OB Limited here. I did my front/rear diffs at 25kish and soon will be at 125k and I'll do them again. I used Amsoil first but the next change will be Chevron synthetic 75/90 front and rear.
How did it look at 25k? I'm thinking about doing my initial change at 10k and then every 60k or so.
 
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The service is recommended every 60,000 miles conservatively. Is there any reason why you want to do it or think that you need to do it at such a lower interval?
I'm OCD and like to waste money...😂 Honestly, to get all the wear metals/high iron flushed out. As I stated before, I'm going to do a change at 10k and then every 60k thereafter. Subaru actually recommends every 15k for "severe service". We meet some of the criteria for severe service, but not all.
 
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How did it look at 25k? I'm thinking about doing my initial change at 10k and then every 60k or so.
Looked pretty good. I expected more small slivers of metal than were there.

I can understand the initial 10k to get break in out. What makes you want to do 60k after that?
 
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Looked pretty good. I expected more small slivers of metal than were there.

I can understand the initial 10k to get break in out. What makes you want to do 60k after that?
I thought that's what the manual said, but I could be wrong. I'll have to double check. I was going to go with whatever they recommend or probably a little sooner.
 
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Actually just checked my manual and the only time it says to replace the transmission fluid or rear diff fluid is under the "severe service" usage and that is every 15,000mi. Normal service it just says "inspect" every 30,000mi which I find odd. 🤷‍♂️
 
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Actually just checked my manual and the only time it says to replace the transmission fluid or rear diff fluid is under the "severe service" usage and that is every 15,000mi. Normal service it just says "inspect" every 30,000mi which I find odd. 🤷‍♂️

Subaru also says to do plugs on the 3.6 at 60k. I did 105k and posted up pics here. They ran fine and looked really good. Others on Subaru sites have also reported similar findings.

I'm doing my front/rear diffs about 115/120k which would be 85/90k since the first time. After that I don't believe I will do them again. I look for 220k-250k outs this ride.
 
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Subaru also says to do plugs on the 3.6 at 60k. I did 105k and posted up pics here. They ran fine and looked really good. Others on Subaru sites have also reported similar findings.

I'm doing my front/rear diffs about 115/120k which would be 85/90k since the first time. After that I don't believe I will do them again. I look for 220k-250k outs this ride.
Thanks for the info. Do you have a link to those plug pics? That's good to know.👍
 
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