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GL-4 and GL-5 Gear Oils


rmbhs
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I found some interesting information asserting that GL-5 gear oil is not backwards compatible with the GL-4. As the pathfinder transmission requires GL-4 this is obviously an important consideration. This was new info. for me. If your interested let me know & I'll email you the info. It's 11 pages long, so too long for a post.

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I saw the same thing while researching the proper fluid for my 2000 Frontier 5 speed. Seems like these stick transmissions like GL-4 but the GL-5 will eat away at the brass parts from what I have heard. Amsoil makes a good replacement that I have been using for a while.

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GL5 gear oil can be corrosive to the brass sequencers. If the manual states GL4, only use GL4. Unfortunately typical product advertising misrepresents this by stating their GL5 "surpasses standards of lower GL oils" letting the consumer believe they are better off with GL5 than the recommended GL4.

 

I have used redline MT90 GL4 trans gear fluid in my 480AWHP Mitsubishi Evo8 for 120K miles, I change it about every 15K. The drivetrain has been through 3 clutches but the tranny is still holding solid. I only use the sulphur laden GL5 stuff in the diff cases.

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Only use straight GL4 fluid in the Pathy's manual transmissions, this means "GL4" only, not GL5, GL5/GL4, GL5/GL4 Compatible, etc...

There have been many cases over the years that owners (several have been members here) have drained a 5spd and refilled with one of the GL5 fluids, only to have them fail some months later.

 

Straight GL4 may be harder to find and possibly more expensive, but putting GL5 in place of it, is just not worth the risk.

 

 

I personally use and recommend the following

 

I have used redline MT90 GL4 trans gear fluid

 

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Redline makes MT-85 which is the factory spec for the Nissan tranny. When I ran straight MT-90 in my long gone 89, the tranny got a little notchy in the winter here in the Northeast. The guys from the warmer climates would never notice this I would imagine. I have posted the specs of most of the good GL-4 gear oils in the past if they are still available via search. The cure for the notchy tranny in the cold was to mix some MTL with the MT-90. With the MT-85 that is no longer an issue. I still have the Nissan 75W85 in my 92 tranny and still shifts quite smooth. I'm going to need a clutch in the near future and I will most likely change it then. If I can get a deal on the Nissan stuff I would definitely use that again, but the last time I checked the MT-85 was cheaper.

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  • 3 weeks later...

The cure for the notchy tranny in the cold was to mix some MTL with the MT-90.

I remember the redline MTL cocktail I tried to help the notches, it was the same recipe (1 qt MTL + MT90). It didn't help much so I lived with it. Interestingly, the notchyness gradually disappeared over time.

 

Guess it takes 100K miles to break in some of these solid import tranny's.

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  • 4 weeks later...

Yeah when I was looking I could not find straight GL-4 anywhere local in anything but a 5 gallon bucket and that was from a fluid shop. So I had a parts store special order Redline MT-90 and had it in a couple days.

 

 

But the bottom line is, make sure that it is just GL4 before you buy it. I had a few parts stores tell me that this and that was gl4, but when I read the bottles for myself they were "GL4 compatible", which generally means that they are actually GL5. "GL4 Compatible" is not compatible with out transmissions.

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