Trans fluid - 80-90 gear oil or straight 40 motor oil

[qz30tt]

I know this subject has been beat to death but I keep finding conflicting information. Should I use 80-90 gear oil or straight 40 weight motor oil in my 1952 M37's transmission?

Thanks

 

[WarrenD]

Stick with the gear lube. GL-4 is the best, NAPA carries CRC 85-90 in the GL-4. Gear lube contains additives for pressure that you won't find in motor oil.

 

[Westech]

yes gear oil NOT Deuce trans fluid... there not the same trans.