OK, so the CRF450 has two oil systems, engine and gearbox. I normally use Amsoil full synthetic like 20W50. Do I use that in both oil systems or do I use different oil in each?
Also, what are the factory capacities for each system? No, I don't have a manual.
That will work in both sides of the engine. The clutch action and shifting may work better with a lighter weight oil, but it seems to vary from bike to bike.