On my 82 Shovel, it has a 4-speed transmission, the book calls for 20-50 SAE, I believe. I have a buddy with a year older Harley, 4-speed, who uses 80 wt. I'm thinking about going to it. The light weight I'm using now tends to weep a little oil. Any thoughts on this?
Dave

Good question, does the thicker oil leak less?
Gotta ask ya, what happens in cooler/cold temps?
I just replaced my tranny oil with 20-50 Mobil 1. Seems to leak about the same or less.
When I park after a ride i still get a couple drops out of the tranny output shaft seal.
Just marking my territory... LOL

I don't know, Roadking, but it is pretty discouraging since my whole tear down rebuild project on this bike was the result of a output shaft leak!!! Although i did slow it down considerably. Possibly there is no such thing as a old Harley NOT marking it's territory.