I can speak as a man who used BAR OIL by the fifty gallon drums and ran chainsaws for a living year in and year out. As a professional faller and bucker I would pour a gallon to a gallon and half of saw gas through a chain saw in a six hour period. Using used motor oil is a rotten idea even though some one else will say they use it. BAR OIL is made to minimize wear on the bar and chain at the same time. Have I cut the BAR OIL with gasoline, diesel, kerosene, in the bitter cold? answer is yes. Have I used regular motor oil of every configuration and hydraulic oil in a pinch? yes. Used motor oil, the risks of screwing up your oiler assembly and or filter make for me, the use of used motor oil a foolish option. Loving your saw as your work partner means you feed it right.