I'm looking for some GL-4 75w90 gear oil for my 95 GSX (and Evo). I've checked all over locally, seems no one carries it, only the GL-5. Through various places, I've be told NOT to use GL-5, even though it's superior blah blah blah..

Being unable to find a local source, I called the dealership (parts division), figuring I'd pay out the ***, but I could get done tonight. They had no clue of the GL-4
I asked what the hell they use then, and he replied, GM Synchromesh...

WTF?!?!! It sounds to me like the dealer isn't even using the correct oil for the job, makes me feel safe...

Any thoughts?

 

Ur dealer is stupid if they don't know what GL-4 is. Basicly it's gear fluid, all 75-90 should work fine. Use what the owner's manual recommends. I tohught it was GL-5 for the rear end, and GL-4 for the tranny/center diff. I don't remember it's been a while since I changed my fluids in my GSX. Then again I used redline in all the cases.

 

Many, many people in the dsm/mitsu world use GM syncromesh. It is supposely very good. I would use this if I was you.

bryan

 

GL-5 rated gear oil provides the greatest extreme pressure protection. It is also "slicker" than GL-4 .

GL-4 rated gear oil is usually used in manual transmissions because the synchros need a higher coefficient of friction to "grab" between shifts. GL-5 can, and often is, used in manual trannys. It does provide the extra gear and bearing protection, but sacrifices some shifting (synchro) performance because it is so slick. GL-5 also is known containssulfites (or more sulfites) that can be harmful to brass synchroswhen combined with very high tranny temps.

Gl-5 is synthetic and more often used in the rear ends of RWD/AWD cars with or without LSD.

 

Very well put rogue

 

Nice response, thank you. I've since checked other sources etc. It seems the GM Synchromesh is the best stuff going
I'm now 42$ poorer, but have 4 quarts of the stuff