All the stats I have for that saw list it at 20-1. If I was going to run it, I would get some good synthetic and mix it at whatever they recommend and use that. I think the one I am using now is 50-1 or somewhat. Why not use some new tech to make old tech last longer. Course if it was mine, I would not use it to cut firewood anyway. You do realize that saw was last produced in 1982, you darn near have an antique on your hands. I have some I run for fun, but the one in the pic has never touched wood and never will. At $200 you got a great collector saw. If you gotta use it for wood, enjoy.