Transmission Oil?

[ForcedFirebird]

Shouldn't use anything but GL-4 variants, GL-5&6 will eat at yellow metals (ie brass synchros)

[JinormusJ]

So then I assume running a GL-4 gear oil in a red tag tranny is acceptable?

[ForcedFirebird]

MTL or MT90 is all I will run in any of them and we service several track cars.

The Chump car we just started working on had the 5th gear syncros go out just after 2 races when the owner put the wrong fluid in. Gear oil is gear oil, these transmissions require manual transmission lube.

Not only that, Redline is less expensive than most other brands, it's a win-win. Why go against the grain of proven results?

[JinormusJ]

Luckily I got some MT90 lying around from my last swap

[digger]

The difference between MTL and MT90 is mainly viscosity ?

doesn’t get below 30F here but gets upto to 120F in extreme cases I guess the thicker is better? might make a light weight FW a bit quieter not that mines that noisy?

I have no idea what’s in there at moment

[jbontke]

I think you only want GL4, as GL5+ (if I remember right) can cause syncro wear: https://www.rtsauto.com/getrag-rattl...-alleviate-it/

[digger]

I think you only want GL4, as GL5+ (if I remember right) can cause syncro wear: https://www.rtsauto.com/getrag-rattl...-alleviate-it/

Both are GL-4

[jbontke]

Both are GL-4

Correct, MTL and MT90 are both GL4. I was speaking in general, as MT90 is not the same as 75w90 because of GL5. Even thought the weight is the same, the additives are not.