Back when the 2 cycle engines were in their heyday, they had mechanical tachometers with hour meters. It was actually calculated by total revolutions of the engine instead of time. Leaks usually didn't show up several thousand hours. With a Cummins, 100 hours a week was common. A Detroit would show more hours because they operated at higher RPM. Although multi vis oils might meet Detroit specs, I would put in a straight oil. 50 wt used to be common in the summer in Texas.
