I run ND40wt in summer/ ND20wt in winter, six month oci's. I have a single lung two gallon craftsman oil lube, ran factory fill five hours. Ran supertech 20w50 for a couple of years, current fill four years on mobil1 15w50.
Ken
i use m1 10w30 ep in mine, works well, and seems to do better than a/c oils in the extreme cold. my ingersoll manual specifys either ac oil or auto synthetic 10w30