6mt AWD Transmission Fluid Selection

[Vspec]

Vehicle: 2004 Subaru WRX STi
Mileage: 73,200
Current Fill: Amsoil SVG 75-90
Previous Fill: Specialty Formulations =(
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According to the Factory service manual the transmission in my STi is speced for Gl-5 75-90 Gear Oil.

The Subaru Boards have MAJOR discussion on what is best to use, some people mix up to 4-5 gear oils to get the desired feel, however that is mostly with the WRX Transmission which is more prone to breaking.

Im trying to compare Amsoil SVG 75-90 to Motuls Gear300.

Which would you guys say is the better all around gear oil?

 

[benjamming]

AMSOIL White Paper on Gear Oils

 

[SilverGGA]

Vspec, please let us how it peforms after you have some miles with the Amsoil SVG, and maybe a comparison with the SF MTL-R will be great! I am currently on SF MTL-R too, but will need to switch to something else in ~8k miles.

Is there any reason why you picked the SVG over the FGR? Pablo here recommends the FGR because FGR does not have any extra LSD additive, while the SVG has some.

However, quite a few people have used the SVG in the WRX 5MT without problems. So I don't think there's any need to worry.

 

[The Critic]

For the transmission, use MTG 75w-90, as it is formulated specifically for transmissions.

Use SVG for the differential.

 

[Vspec]

^Thats completely incorrect.

The rear R180 Diff in the STi requires a 90w only gear oil. One of the only available is Motul 90PA.

And according to Amsoil engineers who I spoke with on several occassions they recommended the SVG 75w90 for the 2004 Surtrac equiped STI 6mt Transmission with Front Diff.

 

[Vspec]

What im trying to figure out, is Motul Gear300 75w90 vs Amsoil SVG 75w90.

 

[The Critic]

Quote:

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^Thats completely incorrect.

The rear R180 Diff in the STi requires a 90w only gear oil. One of the only available is Motul 90PA.

And according to Amsoil engineers who I spoke with on several occassions they recommended the SVG 75w90 for the 2004 Surtrac equiped STI 6mt Transmission with Front Diff.

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You're right, I was wrong. The STi does require a GL-5 75W90 for the manual transmission, so SVG is the correct lube.

However, Amsoil does recommend SVG for the rear differential.

 

[Pablo]

Quote:

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Vspec, please let us how it peforms after you have some miles with the Amsoil SVG, and maybe a comparison with the SF MTL-R will be great! I am currently on SF MTL-R too, but will need to switch to something else in ~8k miles.

Is there any reason why you picked the SVG over the FGR? Pablo here recommends the FGR because FGR does not have any extra LSD additive, while the SVG has some.

However, quite a few people have used the SVG in the WRX 5MT without problems. So I don't think there's any need to worry.

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Exactly. No need to worry.

In theory FGR should shift better. You don't want ALL the same LS additive, FM's, EP's, AW agents as a pure differential fluid in a gear box. Some gear box synchros don't mind, others do.

Amsoil FGR 75W-90 GL-4, GL-5.

 

[gtx510]

How come no one tries Amsoil AGM or Redline 75W90NS?
Those sound like they'd have less FM additives while still having the EP additives that the front diff needs.

 

[Pablo]

Amsoil AGM? It would probably work. Mainly I don't recommend it because AGM may be a bit viscous in really cold weather and I see no advantage over FGR. BUT it does have one of the best anti-foam packages on the market.

 

[gtx510]

Good for a river fording rally car?