Bar oil is worth the extra dollar.

Use bar oil. Motor oil works in a pinch, but it’s thinner, flings off faster, and doesn’t stick to the chain. That means more wear, more sharpening, and a messier saw.

Bar oil has tackifiers that keep it clinging to the chain at high RPMs. Motor oil is designed to stay inside an engine, not lubricate a spinning chain at 10,000 RPM. It’ll sling off into the air and onto your pants, not the bar groove.

If you’re out of bar oil and a tree is half cut, sure, dump some 30-weight in there to finish the job. Then refill with real bar oil immediately. Don’t make a habit of it.

Cheap bar oil is still better than expensive motor oil here.