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2015 Forester I-Premium 6MT
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2,362 Posts
Discussion Starter · #1 ·
The fact that the front diff shares a sump with the mt makes it somewhat picky (IMO) on your fluid selection.

needing a GL-5 for the hypoid gears, yet the right friction for the synchros.

What I have used:

Stock?- Ok felt abit loose when hot and abit stiff when cold not excessively bad

Subaru extra S 75w90
bought 5qt at the dealer out of his 20L mini drum. Cost was aprox 8-9$/qt- Immediately was worse than stock fluid. Had trouble getting it into first and second in [email protected]
Gave it a week it didnt get better.

Now I didnt see the tech fill it out of the mini drum so I'm not 100% positive they actually gave me Extra-S.. on the other hand they lose nothing by not giving me the right fluid.. its not out of their pocket.
Was definitely gear oil of right viscosity though.

This was replaced after a week with supertech 75w90 gl-5 syn blend at walmart Cost 4.69$/qt

Fluid worked ok about the same as stock. I left it in for 2000 to flush out the Extra-S, performance when extra cold was somewhat lacking. In the search for something that shifted better cold

Refilled with Redline 75w90NS

Was immediately better than the supertech, not amazing but better.
Cost ~~15/[email protected](local :biggrin: )

This was left in until recently. The car sees some towing and I felt the shift feel was deteriorated slightly, but not significantly.

Also it was time to change out the 6MT in my father's 2013 outback

Decided to order up a cast of motul gear 300 (75w90 gl-5) off amazon
usually near 18$/qt it was 160/12qt on amazon.
or slightly cheaper than the 14.95+tax redline usually is(might be upto 15.95+tax now)
gear [email protected]

Its the best so far, but not amazing better. Seems to work similarly good in the outback 6mt.


I was considering some of the "Brews" but would rather stick with something more "conventional"currently.
 

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2010 2.0 X 5MT on LPG
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96 Posts
i changed factory oil at ~30.000miles, put eneos (japanese brand ) synthetic for differential, all good
 

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2014 Forester XT CVT
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31 Posts
I have been consistently impressed by Redline MTL. Not sure if it is a suitable substitute in the Subi though.
 

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2010 Forester 2.5X
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1,692 Posts
Well, you have spent some money changing oils a couple of times. Thanks for that.
I am too cheap. I changed my trans and dif. oil at 10k miles. And then again at 40K miles.

I used Walmart Supertech, and it shifted better than what was in there from the factory. I do know what you mean about the sticky 1st gear shirt when cold, and I just think it's the nature of this transmission. We don't get cold here in Los Angeles though.

Just can't pull $10 out of my pocket for a qt. of oil....some kind of block I have.

I asked the parts department at my dealership what kind of gear oil they were using to service Manual trans.. they said just put in any 80W90 GL/5 without LSD modifiers. It looked to me like they were using Mobil bulk gear oil there.

I say put in the cheapest oil that works.
 

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03 Forester XS MT
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208 Posts
I've used Subaru Extra-S in mine and it was great. I'm now using BG Ultra Guard 75w90 and it's excellent. I normally wouldn't use a BG Product, but this particular gear oil is a PAO based oil and is formulated probably by Lubrizol or one of the other larger suppliers/blenders.

http://www.petrotech.co.il/PetroTech//userdata/SendFile.asp?DBID=1&LNGID=2&GID=534

I only found out about this fluid because the dealer near me carries it.
 

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2007 XT Sport 5MT
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24,014 Posts
I've been running the Wal-Mart Supertech fluid since my transmission axle seal went back in 2011. I do agree that it gets difficult to shift at cold temperatures, but it easily performs as well as the stock non-ExtraS fluid that comes in the car.
 

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166 Posts
I have had my better results with Extra-S and Motul gear 300, so that is what I fill the turbo Subarus with. The n/a beater Subaru gets those oils if I have it around come change time, otherwise 75W-90 gear oil from Farm and Fleet (cheaper than Superterch) and works fine. Based on your experience with the Motul 300, I suspect that the dealer "filled" from their gear oil barrel which is most likely not Extra-S.

v - yea it is hard to be certain if you don't see it come from the container. I think your logic is sound and Motul is still a great gear oil.
 

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2015 Forester I-Premium 6MT
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2,362 Posts
Discussion Starter · #8 ·
I have had my better results with Extra-S and Motul gear 300, so that is what I fill the turbo Subarus with. The n/a beater Subaru gets those oils if I have it around come change time, otherwise 75W-90 gear oil from Farm and Fleet (cheaper than Superterch) and works fine. Based on your experience with the Motul 300, I suspect that the dealer "filled" from their gear oil barrel which is most likely not Extra-S.
I dont think they did but unfortunately nothing else would really explain how bad it was compared to what I was expecting from other people's results. Felt wierd,Possibly it had FM's also.



4Mogger
Redline MTL is gl-4 not the right gear oil for subies. The correct redline oil is 75w90NS, The MTL wont provide enough protection for the hypoid gears in the differential that shares the MT fluid, would probably shift better though.


Trailangel-

I have no problem buying quality gear oil. I didnt plan on changing it that much but the whole "extra-s" debacle necessitated it.

This last change with Motul was abit early but I was being the test dummy for it before using it in the 2013 outback.

Also got 1/3 off retail through amazon.


So far I'd say if you want to be cheap the supertech at <5$ qt is a great value.

If you want better performance the motul and redline are noticeably better
 

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SG9 Forester XT Stick Shift
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1,667 Posts
I am running Mobil Delvac 75W90 for the last 20 K miles and it still shift flawlessly even in -10 deg F weather we have now.

Previously I use OEM, Extra-S and Motul with 1 qt of smurf blood. The Motul with smurfblood combination give the best feel but I took it out due to some build up concern that some people get with this mixture and since its considered racing lubricant it would need short drain interval.

I believe the Delvac are another good option for everyday use since it does not need special mix and short drain interval. I bought mine from Zoro tools for $50 for one gallon with free shipping.

As for Redline 75w90NS I heard a few people have problem with it.
 
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