MT trans fluid spec
 

Hi guys.

I just want to know your opinion about API spec for our MT fluid as i searched a lot about it and found that many people said use GL-4 spec but when I go for owner manual. It said GL-3 or upper grade or even in the 2018 manual which i found in online also spec for API GL-3, 4 and 5. Does GL-5 really safe for the synchromesh?
https://i.ibb.co/JzK45wR/Screenshot-...1760772867.jpg https://i.ibb.co/wWhsbQY/IMG-20210530-165906.jpg

I know people on here swear by Motul Gear 300 which is GL-5 but my transmission felt like complete trash with that fluid. It was like a 1990s domestic. I have had great luck going to Red Line MT-90 which is GL-4. What I remember from looking for answers was that GL-4 was better than GL-3 in every way but GL-5 is fundamentally different and can attack yellow metals.


https://bobistheoilguy.com/forums/th...vs-gl-5.37720/

GL4 is fine for the gearbox, however GL5 is not recommended at all, do not use GL5 in the gearbox. GL5 for the differential only.

Whats wrong with the factory fill??

I found the OEM gearbox oil to have very poor cold weather performance. Switched to Redline, and it's way better.

Motul Gear 300 is GL-4/GL-5 rated, so fine to use in our transmissions and won't damage any yellow metals.

https://d23zpyj32c5wn3.cloudfront.ne...pdf?1492016023

That said, I don't think it's any better than stock for cold shifts. I use it primarily for the shear protection at the track, but if I was doing a lot of daily driving, I'd probably try something else (like the Redline MT90 you mentioned).