GL-4 or GL-5

[MolaKule]

Originally Posted By: BrandonVA
yea, i misread the manual. It does indeed say gl-4 or gl-5. Anyway, I just want the best possible protection for my transmission.


You don't need a GL-5 fluid.

You need a dedicated MTL with a GL-4 protection rating as you will find in my post above.

Most of those specs were written by old-school, out-of-mainstream-science engineers before good, dedicated MTL fluids became available.

 

[Al]

Originally Posted By: MolaKule


So the answer is, NO, not for Manual Transmissions.

Thanks Mola

 

[BrandonVA]

i have the redline mt90 now. shifts pretty good but still getting a whining noise in 2nd gear. I know gl-5 is supposed to offer better protection so I'm going to try amsoil severe gear and see how it does. I've heard that it works pretty well in the c59 transmission despite what most people say about gl-5's.

 

[antiqueshell]

Originally Posted By: BrandonVA
i have the redline mt90 now. shifts pretty good but still getting a whining noise in 2nd gear. I know gl-5 is supposed to offer better protection so I'm going to try amsoil severe gear and see how it does. I've heard that it works pretty well in the c59 transmission despite what most people say about gl-5's.


The GL-5 may appear to work well, HOWEVER, it may shorten
the life of any soft metal components. I doubt that whine will go away with the GL-5. It is most likely either a trait of that unit or a more serious mechanical issue.

When it comes to virtually ANY synchronized manual transaxle unit you should be using a GL-4 fluid only, even if the owner's manual claims you can use GL-5, in the end the GL-5 may work adequately
but shorten the life of certain soft metal components and make for
more difficult shifting.

A most important fact to remember is that the GL-5 spec is not
an update of GL-4. They are two very different specs designed for different applications.

GL-4 is NOT obsolete in any way.

 

[MolaKule]

Originally Posted By: BrandonVA
i have the redline mt90 now. shifts pretty good but still getting a whining noise in 2nd gear. I know gl-5 is supposed to offer better protection so I'm going to try amsoil severe gear and see how it does. I've heard that it works pretty well in the c59 transmission despite what most people say about gl-5's.


Offer better protection from what?

If your bearings are worn or your gear teeth are worn, nothing is going to reverse that situation.

The only thing Severe Gear might due is quiet the whine a bit because because it is thicker, but your shifting may suffer because it is thicker and does not a have the MT specific friction modifiers for the synchro.

 

[MD1032]

You really think you're going to get better protection than this? MT-90, C59 transmission, 54k mile run.



I used MT-90 for almost the entire time I had my 2005 Corolla 5-speed, which was over 130k miles, and it was fantastic. Huge difference in shift feel over stock, especially in the cold. I can't say it is the best fluid for that car, but I can say that guys who ran GL-5 in that transmission had problems with their synchros afterwards. You should not use GL-5 in that transmission.