So I was looking for Redline MT90 for my tranny refill for tomorrow and couldn't find it at any of the local stores. I found Royal Purple ($15/quart ) 75W90. Will this be ok? I know people love his oil and $45 for a tranny fluid isn't too bad if it will last 2 years/30K miles.

Is MT90 just a GL4 spec 75W90?

 

AMSOIL MTG GL4 100% synthetic keeps everything inside clean

It is formulated specifically for maximum protection in the most demanding manual transmission and transaxle applications where an extreme pressure GL-4 gear lube is specified, including those where high horsepower/high torque engines and towing or heavy loads increase transmission stress.

 

i'm using the RP 75W90 in the tranny. at a cold start up, shifting is much more notchy then oem. gears grind slightly if you shift too fast when the tranny isn't up to operating temps. when it does fully warm up, it a little bit smoother than oem. i'm probably going with a different fluid when i hit 60k

 

Well that's lame. It feels like my shifter is catching the gears randomly right now. I have 29K miles on it, so hopefully it makes it somewhat better. Either way, it's time to replace it. Got a freak heat wave (45F) for tomorrow, so no time like the present.