Subaru Extra MT Alternatives?

C

Clarkbug

Joined
May 5, 2012
Messages
74
Location
NY
Good afternoon Everyone.

I did a little searching on this, but didnt see any definite conclusions anywhere.

I have a Subaru Forester with the 6MT, and I see in the manual it states to use Subaru Extra MT. (Not to be confused with Extra-S, or the HPGO. Here is a handy link: https://content.subarunet.com/snet/_content/fixed_operations/oil_program/mt_gear_oils.pdf )

I know there is an option to use a GL5 75w-90, but also know the transmissions are a little bit picky about what goes in them it seems, and its hard to get a good match of protection for the diff as well as the synchros. Is OEM the way to go here, or is there an Amsoil/Motul/Delvac alternative that should keep things happy?
 
I like redline 75w90ns
but the motul gear 300 was better.

Shifts better except in extreme cold vs the oem.

IIRC Need 4liters uses just over 3.25qt
 
I've tried the Redline 75W90NS, and while good, it was not as good as the Motul Gear 300.

The Motul is what I use in every Subaru diff I own or service (that number is now at 9 vehicles and counting); for 4EATs I use MaxLife ATF in the tranny but still Motul in the diffs. It's worth every penny.
 
My WRX also states Subaru Extra MT. I have used Subaru 75W 90 high performance gear oil instead. Changed two times changes were at about 35K intervals. The car is at 75k now no issues.
 
Last edited:
It's been a while, but I remember back when Subaru's recommendation was solely for GL-5 75W90. I'd tried all sorts of lubes including Red Line 75W90NS and Motul Gear 300. I did have this really odd reverse gear failure back in 2010 but I can't attribute that to the gear lube. Someone I know actually rebuilt it because he couldn't find a used or rebuilt transmission and handed me the reverse idler gear that had a couple of broken teeth as well as a few bent ones. Said it was highly unusual for straight gears to break. But he had access to Special S and I believe that's what's still in there. I haven't bothered to change it since since I'm kind of lazy and technically they only say to inspect it and change if there's an issue. It's not low so I haven't done anything. Shifts are still good. I'd like to change it again if I could get Special S, but not sure if it's still available and I can't find my tools - especially that oddball T-70 Torx bit. Do they still use that?
 
Originally Posted by y_p_w
It's been a while, but I remember back when Subaru's recommendation was solely for GL-5 75W90. I'd tried all sorts of lubes including Red Line 75W90NS and Motul Gear 300. I did have this really odd reverse gear failure back in 2010 but I can't attribute that to the gear lube. Someone I know actually rebuilt it because he couldn't find a used or rebuilt transmission and handed me the reverse idler gear that had a couple of broken teeth as well as a few bent ones. Said it was highly unusual for straight gears to break. But he had access to Special S and I believe that's what's still in there. I haven't bothered to change it since since I'm kind of lazy and technically they only say to inspect it and change if there's an issue. It's not low so I haven't done anything. Shifts are still good. I'd like to change it again if I could get Special S, but not sure if it's still available and I can't find my tools - especially that oddball T-70 Torx bit. Do they still use that?


You cannot get Extra-S anymore, so unless you find someone with part of a pail left, you are out of luck. I believe its still the Torx bit, but might be different depending on your year.

Originally Posted by SubieRubyRoo
I've tried the Redline 75W90NS, and while good, it was not as good as the Motul Gear 300.

The Motul is what I use in every Subaru diff I own or service (that number is now at 9 vehicles and counting); for 4EATs I use MaxLife ATF in the tranny but still Motul in the diffs. It's worth every penny.


Thanks for the advice, thats good to know. I have heard good things, but wasnt sure how it behaved in the 6 speed.

Originally Posted by maxdustington
Redline, or ask on a Sube board.


You know how oil threads go. Thats why I figured I would ask on an oil board. Plus the most active seems to be NASIOC, and I dont want their snark or to hear about Uncle Scotty's Cocktail any more.
 
Originally Posted by Pablo
Amsoil 75W-90 in cold places, Amsoil 75W-110 in warm places.

Amsoil 75W-90

Amsoil 75W-110



I am definitely in a cold place.

Looks like it comes down to Redline, Amsoil, or Motul as options if I dont want to spend the $$$ at the Dealer for a five gallon pail.

Does anyone know if Idemitsu is still making this for Subaru?
 
So I have done some more searching, and came across motylgear, which appears to be a semi-syn. I see they have a 75w-80 grade, and I wonder if that would be comparable to the Extra-MT...
 
Originally Posted by Clarkbug
Does anyone know if Idemitsu is still making this for Subaru?

As far as I know the US dealers can't get Extra S any more. What they have now is part # SOA427V1700, which says "Certified High Performance Gear Oil 75W90" and is made by Idemitsu.

[Linked Image]
 
Originally Posted by Clarkbug
So I have done some more searching, and came across motylgear, which appears to be a semi-syn. I see they have a 75w-80 grade, and I wonder if that would be comparable to the Extra-MT...

I tried the motylgear 75w80 a week after changing the factory fill oil with the motul gear 300 oil. The car is a 2014 6mt outback. According to the manual, the factory fill was the extra mt oil. Shifting with the gear 300 oil wasn't smooth at all. That's why I decided to try the motylgear 75w80. Shifting is now very similar to what it was with the factory fill. It's considerably smoother than it was with the gear 300. It also smooth while cold; morning are still at 0C - 5C in april here in Quebec City.
 
Thanks for the feedback, and letting me know that it worked well for you! Please post back once you have a few more miles on it to say if the feel has stayed the same. ( I know thats not scientific, but helps to know anyway)
 
I have a 16 WRX and the 6sp was a little finicky when I bought it with 38k. I am not sure if it was still with factory oil or if prev. owner changed it. I changed to RedLine 75w90ns and it didn't improve. It still takes a 2 sec. hesitation between clutch and first when stopped or else it grinds. While traveling it does ok, but not great. Doesn't grind at all unless I get lazy. Research told me the synchros need oil without a lot of LS additive or this happens, and that was why I am RedLine NS - over Amsoil or M1 etc.. I may try Motul when I change again in the near future. Anyone have updates to this post?
 
Redline has told me that LS additives interfere with synchro engagement. Tribologists have pointed out otherwise. The LS additives aren't the crux of the issue; one needs specialized friction modifiers for correct synchro engagement. Since it is a gearbox with a differential, it needs GL-5 level of EP protection (to sufficiently serve the differential) and be additized for a synchronizer-equipped gearbox. Motul Gear 300 is the only one I know of that is truly formulated this way.
 
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