What’s the bar and chain oil made out of that makes it “non toxic” to the environment? Didn’t I read here that it is made with crude oil, same as motor oil? Maybe there are some vegetable based bar and chain oils, but I don't see them being promoted as the only way to go.
And at least on the oiler of my saw, it hasn’t harmed it in 25 years.
In 25 years I have gone thru 4 bars, and never seem to have a problem cutting. Keep the chain sharp, and even in Locust or White Oak, she throws big chips and cuts as well as my buddy’s larger Husky (not sure of the model) in which he uses some brand of “bar and chain oil”.
Used oil is just what I was taught to use, and never gave it much thought.