Rear differential fluid-2016 Subaru Forester 2.5

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R18A1

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Hello bitog,

Will be looking to change the rear differential fluid in my 2016 Subaru Forester 2.5 FB engine vehicle. The vehicle has a good mix of in town and highway driving (40/60) and will be seeing cold temperatures in the winter months.

I believe the rear diff calls for a GL-5 75w90 weight lube. I was thinking of going with Petro Canada Traxon or Amsoil severe gear for a 100000km interval. Or maybe I should stick with the subaru oem gear fluid?

Looking forward to hearing people's thoughts and opinions on this!

Thanks in advance
 
Put any GL-5 75W-90 gear oil in and you'll be set for a long time. It's an open rear diff.

When choosing a gear oil for my previous STI, I was told by Redline that their Shock-proof was way overkill, even for that application. They told me their regular GL-5 lube was good to go.

Not wanting to listen, I went with the best gear oil (on paper), Motul Gear 300.
 
I also have a '16 Forester with a 2.5. I did the front and rear diff fluid a few months ago. Used Schaeffers 75W-90. No problems, no strange noises. Gas mileage stayed the same. I'm pretty sure any GL-5 75W-90 would be fine.
 
On my 2016 Forester 2.5FB, CVT, I swapped out the factory rear diff oil with Napa full synthetic 75w90. Same with my 2014 XV Crosstrek. Hope the current owners appreciate it. I never did touch the fronts on any of my Subarus.
 
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Motul 300, while a great fluid, is only recommended for a 30k service life. That is disappointing for what you pay for it. I used Delvac 75w90 available from Amazon because it is formulated for long service life. Subaru says the diffs are a lifetime fill except for severe service duty. I would recommend at least one change to get the breakin fluid out and then you can run a long service life lube like the Delvac or Amsoil Severe Gear. If you do the front diff I'd think you'd want a once and done approach.
 
I hope you can break those fill and drain plugs loose. I had diificulty and heard horror stories of cracking the cover trying to break the fill plug loose.
 
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Yea make sure you break the fill plug first. I've done front and rear diffs on 5 Subarus to date. Breaker bar with a pipe over the handle and even pressure with correct alignment will break them with no damage to the case. There is no need re-tighten them to the OEM level again.
 
Originally Posted by T-Stick
Motul 300, while a great fluid, is only recommended for a 30k service life.


Where exactly do you find that "recommendation"? I don't see anything similar on the Motul website or PDS. This is what I see on their website:

RECOMMENDATIONS
Oil change: According to manufacturers' requirements and adjust according to your own use.
 
Originally Posted by SubieRubyRoo
Originally Posted by T-Stick
Motul 300, while a great fluid, is only recommended for a 30k service life.


Where exactly do you find that "recommendation"? I don't see anything similar on the Motul website or PDS. This is what I see on their website:

RECOMMENDATIONS
Oil change: According to manufacturers' requirements and adjust according to your own use.


Actually I do not see it any more on their website either. They used to have a Q&A section on their site where they recommended a 30k service interval. I emailed them and asked why I would need to change their fluid at 30K if the manufacturer considered their fluid a lifetime fill unless it was used for severe service. I never received a reply. So I will retract my statement of Motul requiring a 30k service because it is no longer substantiated by their website. The PDS has your citation above so that is the recommendation now.
 
Agreed! I run 50k intervals in the front diff, manual trans, and rearends of the Subarus, but could probably go 100k since they don't exactly generate a lot of motive forces
lol.gif
 
I've wanted to change the rear diff fluid on my 08 Legacy GT (with the LS) but cannot for the life of me get the drain or fill plugs loose! I gave up!

157,000 miles on stock fluid! I did change the front (part of the trans since its a 5 speed) but it kills me to not be able to change it!
 
Get a 1/2" impact and give that drain plug a bump or two. That should free it up
lol.gif


Or, get a fluid pump and open the fill plug, stick the tube in, and suck it as dry as you can get it. Then run a cheap(er) fluid for about 500 miles, then repeat to get as much stuff out as possible, then refill with your fluid of choice.
 
Originally Posted by racin4ds
I've wanted to change the rear diff fluid on my 08 Legacy GT (with the LS) but cannot for the life of me get the drain or fill plugs loose! I gave up!

157,000 miles on stock fluid! I did change the front (part of the trans since its a 5 speed) but it kills me to not be able to change it!

Oh man that would kill me too, have you taken it to a shop?
 
Thinking about this more ... I don't think I would personally use Motul in a long drain application. I know they previously recommended a 30k change interval and I doubt if they reformulated everything. Setting that aside, I do not see info saying that they are specifically formulated for long drain intervals either. So if it were me I would at least use a long drain formulation gear oil in the front diff because they can be fun to change.
 
Originally Posted by racin4ds
I've wanted to change the rear diff fluid on my 08 Legacy GT (with the LS) but cannot for the life of me get the drain or fill plugs loose! I gave up!

157,000 miles on stock fluid! I did change the front (part of the trans since its a 5 speed) but it kills me to not be able to change it!


You give up too easily.

Now get those plugs out and change that nasty fluid!
 
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