SAE 80??

[IMCA38]

The book for my 1971 vintage Cushman Truckster says to use SAE 80 in the transmission. Where on earth does one find SAE 80? I've looked at auto part stores, and places like TSC and no straight weights higher than SAE 40. Can I use something like 80w90 gear lube, or is that too heavy?
Thanks
Todd

 

[BarryinMN]

80W90 gear oil is roughly equivalent to 20W motor oil in viscosity.

 

[Skyco]

Yep 80w gear oil is comparable to 20w motor oil in viscosity but the properties are very different.
Does the manual say which type of oil to use? I would suspect gear oil.

Here is a chart comparing viscosities- EH Oil Viscosity Chart _ large

 

[IMCA38]

Transmission- SAE 80 above 32 deg F
SAE 20W below 32 deg F

Differential- EP80-90 multigrade lubricant