asplundh oil reservoir question?

[wahlturfcare]

i have a 90's chuck and duck and noticed that my oil is starting to get low in the govenor and cant find my manual that says what type to put into it.
would anyone know?

 

[gdavis24]

asplundh governor oil

mine is older chucker, regulator from Hoof mfg. Runs with 20 w oil, like hydraulic oil. have had pump people tell me it should be constant viscosity oil, which they filled as ATF.

 

[NCTREE]

I was told buy the manufacter to just put 10-40 motor oil in it. Don't let it run out a new one costs around 400 bucks.