A 'FYI' to help some sort out this lube thing for any number of applications:
Somewhere in my 'way back' Harley Davidson had '105' and '75' designated motor oil. These were really 60wt and 40wt, and are likely still available if someone thinks a 60wt is needed, but they be pricey. The detergents and additive package wont hurt for general lube. I agree that the 90wt and the multi-grade 'gear lubes' are heavy duty, yet still oils, At the other end ATF has been regarded as about a 5wt equiv. (IIRC). If you want a high pressure, lightish bodied oil there is the hydraulic jack oil; Ive used it for chain lube as it isnt sticky so junk doesnt glue onto my chains. I think I will try chain saw bar lube this year for that too; it also comes in a summer or winter (thinner) wt.
The Gear Oils, ATF, and HJO are readily, and inexpensively available at many big box stores or farm supply stores.
