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Subaru Extra-s gear oil - cat's meow!


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Over on a BMW forum, a gentleman put 75w90 gear oil into his manual transmission (which called for a whole different lubricant).

 

He drove it a couple of miles and said it "shifted like shit". He swapped to a redline fluid and said it felt like glass..or maybe butter....

 

My point is: That guy was an idiot but he thought the was buying the right stuff.

 

Make sure you purchase the correct lubricant for your differentials/trans/LSDs. I'd always recommend posting exactly what you bought on a forum and giving people a day or two to respond. Use the knowledge base.

 

The gentleman I mentioned above didn't know that 75w90 gear oil is different than other 75w90......and neither did I, until I read the responses to him mocking him for his idiocy :)

 

Of course, I wasn't shopping it. So I feel superior.

 

By the way, did someone say LSD additive? Isn't that illegal? And why do subies run well on it?

 

:)

 

Joe

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  • 1 month later...

The Redline 75W90 gear oil seems like it was intended directly for our application:

"Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5."

 

Redline advertises their 75W90NS thusly,

"This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

 

What could be more clear than that? I haven't read anything negative about these fluids. :confused:

 

It makes sense to me that you would need two different fluids for these components.

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  • 2 weeks later...
The Redline 75W90 gear oil seems like it was intended directly for our application:

 

"Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5."

 

Redline advertises their 75W90NS thusly,

 

"This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

 

What could be more clear than that? I haven't read anything negative about these fluids. :confused:

 

It makes sense to me that you would need two different fluids for these components.

 

 

 

 

 

DO NOT USE REDLINE IN YOUR TRANS!!!!

I paid out the nose for this fluid and though I was "upgrading" But I started to get the Syncro grind in 3rd and 5th. I swaped back to Subie OEM fluid oil and got MUCH Better. But if you think your trans is "special" form the rest of ours go ahead just a warning.

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Did I say anything to indicate I thought my 5MT was "special"? :confused:

 

Did you make sure you used the 75W90NS in your transmission, any chance you used the normal 75W90?

 

A.) I was not refering to you as being "Special" It was a general statement

B.)I work on cars for a living, Reading the labels is very important.

C.)Yes It was the right oil.

D.) So if you feel like redline is the product you want to use in you car go ahead it will grind.

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I belive that the subaru center diff is a sealed unit and that the gear oil does not contact the diff itself. Also that the STI's work best at the 50/50 setting and not with the other crazy settings. The legacy is already 50/50 split unless you are doing some serious track events the diffs are the last thing you should start messing with.
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I belive that the subaru center diff is a sealed unit and that the gear oil does not contact the diff itself. Also that the STI's work best at the 50/50 setting and not with the other crazy settings. The legacy is already 50/50 split unless you are doing some serious track events the diffs are the last thing you should start messing with.

 

Correct on all points. Although there are times in the mountains, when I wish I had an STI front diff (04 variant)

SBT

- Pro amore Dei et patriam et populum -
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Correct on all points. Although there are times in the mountains, when I wish I had an STI front diff (04 variant)

SBT

 

I wish my LGT had the whole STI drivetrain.. blah.. Which is why I will probably eventually trade my LGT in for an STI.

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The Redline 75W90 gear oil seems like it was intended directly for our application:

"Our most popular gear oil, this is the preferred product in nearly all car and light truck differentials, both conventional and limited-slip. 75W90 is preferred for most racing applications. It contains friction modifier which is recommended for limited-slip units. 75W90 Gear Oil can be used in many transmissions and transaxles; however, other Red Line lubricants have better frictional properties for rapid synchronization. Exceeds API GL-5."

 

Redline advertises their 75W90NS thusly,

"This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

 

What could be more clear than that? I haven't read anything negative about these fluids. :confused:

 

It makes sense to me that you would need two different fluids for these components.

 

 

Anyone get this figured out.

 

I have the two above RL fluids in my tranny and rear diff. My tranny shifts fine, even at -40F.

I believe that red-line sells the additive separately.

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The point of my post was that it's extremely straight-forward.

 

75W90NS for the transmission.

 

75W90 (or 75W90NS + Friction Modifier) for the rear LSD.

 

The only thing I question is whether the LSD units they recommend the friction modifier for are of the VC type or the clutch-type.

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