sae30 or 10w30 or whatever weight is recommended by the manufacture. I run a specific air cooled race oil in my air cooled engines. You can usually find it in the motorcycle section of the auto parts store. I think Kawasaki mentioned minor oil consumption in the multi formulas is normal. I say that because some auto oils are not recommended with the valve train in my Kawasaki engine. And at only have a few engines that take less than 2 quarts it's not worth trying to save a dollar at oil change time. I do run purolator or wix filters from the auto store too.