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Is Redline 75W90 GL5+ Gear Oil Safe to use in an SR20 M/T?

  • Hell yea, that stuff cost you $11 a bottle!

    Votes: 1 25.0%
  • **** no, $44 or a new tranny, what's better?

    Votes: 3 75.0%
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Discussion Starter · #1 ·
With the revival of the Redline thread, I wanted to know what you guys think about the oil I just put in my tranny...

This stuff is exactly like MT-90 except for the GL5 rating... I went to the only store in the city that carries redline stuff, and this was the closest thing to MT90 I could get... Should I change it or do you think I am OK? Still shifts pretty good.
 

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Undecided
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Not sure. I'm wondering along the same line. I bought Lucas 75w90 Synthetic thats desgined for High performance and LSD equipped trannys. It says its a replacement for GL5 and GL6.
 

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P10 Geek
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The 75W90 is not safe on the Nissan synchros. It will shorten their life span drastically. MT-90 is specially formulated for GL-4 applications like the Nissan synchros.

IMO you should get the correct type and drain your tranny.
 

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The Super Mechanic
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NismoPC said:
The 75W90 is not safe on the Nissan synchros. It will shorten their life span drastically. MT-90 is specially formulated for GL-4 applications like the Nissan synchros.

IMO you should get the correct type and drain your tranny.
What makes nissan syncros so special. They are made of brass
 

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Discussion Starter · #6 ·
I'm gonna call Courtesy, Mossy, and Redline tommorow and see what they say... I kinda don't wanna change the fluid again, but I guess I might have to. Maybe I could just refil the old oil bottles and try to return it :rolleyes:
 

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Pâté Performance...
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supercowboy said:
What makes nissan syncros so special. They are made of brass
It "eats" the brass. Not a good thing.
 

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woo dee woo
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I just did some serious research and i had no idea that our transmissions could suffer damage from a GL-5 oil. When i had to replace my driveaxles back in september i topped off the tranny with some valvoline synthetic 75-90w i had laying around (which is GL-5). i just ordered some redline mt-90 and i will change it out as soon as i recieve it. on the redline site it says that GL-5 will reduce syncro life by half...no good. I wonder how much damage i did by topping off the tranny with GL-5 after the driveaxle swap. It's only been about 6 months.....but i beat on my car pretty bad.
 

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NismoPC said:
The 75W90 is not safe on the Nissan synchros. It will shorten their life span drastically. MT-90 is specially formulated for GL-4 applications like the Nissan synchros.

IMO you should get the correct type and drain your tranny.

I thought mt-90 was 75w90...? :confused: It's just that it's GL-4, not 5.
 

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Discussion Starter · #12 · (Edited)
The guy I talked to at Redline said the same thing that the guy reported on the Redline thread. Bottom line, although the GL5 75W90 doesn't eat Nissan synchros, it does have a friction agent in it that makes shifting harder. I know now to always go with MT-90!

Gonna go across the Golden Gate Bridge to get some MT-90 now.... Some times i don't know whether this forum is a curse or a blessing :redface:

jk, thanks for the input. :D

damn mackenzie...
 

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El Gabito said:
I thought mt-90 was 75w90...? :confused: It's just that it's GL-4, not 5.
I was not referring to MT90. He (ResidentWarui) stated he used 75W90 Redline Gear Oil. There is a difference.

Sorry I did not clarify which Redline 75W90 I was referring to. :rolleyes:

Here:

THIS ONE IS BAD FOR NISSAN SYNCHROS (hard shifts, etc.)
75W90 Gear Oil - 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.

THIS IS THE CORRECT 75W90 TO USE
MT 90 - Manual Transmission/Transaxle Lubricant. A 75W90 GL-4 gear oil which is designed for manual transmissions which require 75W90, or 90 GL-4 gear oils or motor oils. Uses the same chemistry as MTL , but is a 90 WT in order to satisfy certain manufacturers which recommend SAE 90 GL-4 gear oils.
 

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Discussion Starter · #15 ·
Just put the MT-90 in... MUCH BETTER! Shifts into first easier than ever.

Oh yea, and for those of you who made the same mistake I did, don't try to save the old 75W90... In my case I had the GL5 stuff in for about 200 miles and figured I could re-bottle and sell it to some cheap guy for $5/ bottle. Anyways to make a long story short it ended in a huge disaster, big pool of tranny fluid on the floor.... Kinda hard to do this alone without a clean pan that will catch a lot of oil. That fluid really comes rushing out. Glad I didn't try this at home...
 
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