BruceK,
Castor oil is not user friendly.
Unless you race.
Bumpkin wrote;
“As to viscosity it probably doesn't matter, for you, in the Northwest a multi viscosity may serve you better for easier cranking in the winter.”
Right it dosn’t matter. MV oil is not needed since our engines aren’t exposed to outside winter temperatures. Why should I want easier cranking for starting? I went for about 12 years living in SE Alaska using Chevron RPM Delo 30wt. Oil. I had a little heater in the engine compartment so the engine never got below about 40 degrees. But the heater was there mostly for other reasons. Engine didn’t need it. Never hesitated to crank smartly and start quickly w almost no exhaust smoke. All other things being equal oil is better w fewer VI additives and a higher percentage of oil .. in the oil. Most anyone will tell you “buy the oil w the narrowest range if viscosity ratings. Like 0w20 instead of 0w40. The reason is that oil is better w less VI. And of course that’s single grade oil … 30wt. 40wt ect.