G50 tranny fluid. Damage from GL4??

[don911]

Changed the tranny fluid on my G50 a couple months ago. I used Redline gear oil but it is GL4 instead of GL5. I've driven roughly 2K miles. What's the difference between GL4 and GL5....and have I done any damage to my tranny?

[Eric Coffey]

Yes, the car is now useless. Let me know when a good time is to come by and dispose of it for you.


Seriously, I wouldn't worry about it, but would probably switch it out in the near future. AFAIK, the GL (Gear Lubricant) rating relates to the number of EP additives. So a GL0 would be straight mineral oil. I think it only presents a problem when you go the other way (put GL5 oil in a GL4-rated box), as it could accelerate synchro/bearing wear by being too "slippery".

[dvkk]

GL-5 has a better extreme pressure rating. I'd say if you are using your car for racing, change it.

[beepbeep]

Porsche used very steep hypoid angles on their final drive to keep gearboxes compact so it forced them to use higher-rated tranny fluid (even known as tranvestite ejaculate )

So you are probably not destroying anything but are theoreticaly risking more final drive wear...

[don911]

Thanks. I'll change it out. I don't need additional wear on my 210K+ tranny.

[KTL]

Don,

I assume you used MTL or MT-90? Because the other gear oils are GL-5 rated. I inquired with Redline awhile back, and Dave Granquist's recommendation was 1 quart of Redline Lightweight Gear Oil and the remainder Redline 75W90.

You could also try 75W140 since "75W140NS is designed to help reduce the noise in noisy transmissions and transaxles, while still allowing good low-temperature shiftability" per Redline? Just a thought since your trans. has relatively high mileage.

[yelcab1]

I have 180K miles on my engine and tranny. I put Redline RTL into the tranny last Christmas. If it is GL4, so be it. I am running out of things to fix. I am just hoping either the tranny or the engine blows up so I can fix it. But, the car will not cooperate. Grhhh.