Whizzer oil
Hal, it is a low compression, old-style flahead with improed bearings on the bottom end.
It would probably run on crankcase drippings form Flathead Ford cars from the late 1940's!
I use, and will continue to reccomend ANY automotive 40wt engine oil that is clean and you can get your hands on!
We change our oil often, so grand and glorius fancy, madison avenue additives will probably do us exactly no good!
I have used most of the brands on the market here with equal sucess.
The coolest thing I have found about oil changes are these two concepts.
#1 get a pointed "squirt cap" off of a gear oil, or hydrolic oil, or some other bottle so you can squirt a thin stream of oil into the engine.
#2 you can drain your old oil into a ziplock type sandwich back quite nicely!
Mike