I'm pretty sure I filled my saw with 80W hypoid gear oil, that goes in my bikes tranny and final drive, instead of the regular chain oil and ran a tank of gas. The gear oil and chain oil containers are the same size, so I must have grabbed the wrong one, don't know why I didn't smell it when I was pouring it in, or notice the viscosity, but the last bit of oil in the reservoir sure smells like gear oil to me. Guess I'll just dump out as much as I can, refill and carry on. I can't imagine it did any harm?