Subaru appears to allow "Extra MT" or a GL-5 75W90 for the front differential. Google is telling me that Extra MT is a 75W-80 GL-4 lube designed for MT's, which seems awfully light for a front differential.
Does anyone have a VOA of Extra MT?
2025 Forester Front Differential Fluid
- Thread starter The Critic
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Subaru appears to allow "Extra MT" or a GL-5 75W90 for the front differential. Google is telling me that Extra MT is a 75W-80 GL-4 lube designed for MT's, which seems awfully light for a front differential.
Does anyone have a VOA of Extra MT?
Looks like Subaru only sells this in 5 gal drums. Closest matches are Redline MTL, Amsoil MTF and Motul's Motylgear 75W-80.
Motyl is the least expensive product but also likely to be the thickest when cold (highest 40C viscosity and lowest VI).
Ravenol is of a slightly lower viscosity than the 3 above.
Main issue is that the front differential is a differential. A lot of the MT specific lubes do not provide adequate protection for differentials. Does anyone know if Extra MT is a unicorn GL-5 75W80 product?
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I’d just run Amsoil Severe gear or Valvoline 75w-90. I have 20k miles so far on severe gear on my 21 Outback no issues.
Exactly what I did.
I'm sure it's fine, but I would prefer the extra fuel economy. I cannot foresee wear being an issue in this application.
There is a significant viscosity difference between 75W80 and 75W85.
It is a 75W-80 GL-5.
Another option for a GL-5 in that grade is Fuchs Titan Sintofluid 75W-80. It has better low temperature performance than the Motul.
It isn’t, but I also don’t see a reason to use a fluid that is nearly twice the viscosity.
Please read footnote #3 in my original post.
2024 GMC Canyon 4X4. Factory rear gear goo is 75W80. That's too thin to me. GM doesn't state anything about going thicker when pulling trailer. I put Redline 75W90 in rear dif. Guess what happened to MPG??? Nothing, and it got down to 0°.
Also why does Subaru say 1.4qt in the front dif BUT only .8qt in the rear dif???? Seems backwards to me.
Also why does Subaru say 1.4qt in the front dif BUT only .8qt in the rear dif???? Seems backwards to me.
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I've had 80w-90 in my 2012 Legacy diffs for at least 3 years now.
I did read the footnote. My statement still stands. But do what makes you happy.
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What did you end up going with in your OB diffs? I'm doing our 2022 Onyx XT soon and was going to do SVG 75w90 in both front/rear.
I ended up going with Mobil 1 75W-90 from Summit Racing. $10.99 per quart, front and rear.
I just did my Jeep with Amsoil Severe Gear. Good stuff!!
I had my Legacy done with 75W-90 front and rear. Don't know what the shop used brand wise. I haven't noticed an MPG hit in the 14k miles since it was done.
I bought SVG 75W-90 for my Impreza also for front and rear. Haven't had it done yet. This being furloughed thing is making things tough. Was gonna do it last month, but I had to get my sax repaired. It cost more to fix than the labor to have the diffs done and I needed it fixed more than I need the diff fluid replaced.
I bought SVG 75W-90 for my Impreza also for front and rear. Haven't had it done yet. This being furloughed thing is making things tough. Was gonna do it last month, but I had to get my sax repaired. It cost more to fix than the labor to have the diffs done and I needed it fixed more than I need the diff fluid replaced.
