1970-1980 chev 1 Tom dump truck with manual trans fluid.

[IMR]

hey guys we have a 1977 chev square body 1 ton with a 3 Speed trans with L and PTO manual on the dump truck wondering which fluid we go with ?

 

thanks 

[Mikebtte]

I am sure the truck has a set Oil to use. I have always run 80W90 in my SM420 and strait 50W in 18 speed transmissions with PTO.

Head up to the auto parts store and they can recommend something or pick up something at a Semi truck stop.

[Logan Lanfear]

A synthetic gear oil.  Recommended would be found in your manual.  I'm guessing its a SM-465 which has the granny low with 3 more speeds.  Most go with a 85W-90 with a GL-4 rating. Stay away from GL-5 it will eat your synchronizes.