A decent oil that doesn't leave too much junk behind when you mix it pretty rich. Some crud will always happen, but an oil that burns clean is better long term. This engines will be rough and crude at first, but they do smooth out and you will feel the power increase with time. You can run a non-synthetic at first, but be aware of the myth that synthetic oil will extend the break in time.
That'll work. I'm running 2 oz of Sig castor+2oz of Amsoil Dominator in one gallon. 4:128 or better known as 32:1. I wouldn't necessarily recommend nor do you even need the castor oil, it's my experiment, really.