Basically look for a good ashless oil. I know a guy that runs the Mercury Quicksilver in all his engines. I like synthetics. Since the bearings aren't the best in the MVVS engines, I'm planning on running a gallon or so AMSOIL Dominator through it and then maybe do a gallon of Pennzoil Air Cooled at 30:1 for a gallon to get a good ring seat. Then going back to AMSOIL.

Gizmo, were you running the Pennzoil Air Cooled in your outboard? That could be a problem as it is designed for air cooled engines and not water cooled. Back home we don't run anything but Quicksilver in our Mercury 115 or our 25 and 10 and we've never had problems. Oils can be funny.