I was thinking about the recycled oil,,
With transportation costs, risks, and insurance,, the slow process of prep to resell, possible water or gas etc contamination,,
it is more than likely that new crude made into chainsaw oil would be cheaper than recycled..
I would bet most used oil is simply burned in some type of furnace,, much like a local generating facility uses wood chips as fuel.
A local cement plant wanted to use tires as fuel,, but, the stack contamination due to alloying and plating on the steel cords stopped that.
Heck, they wanted permission to put TONS of cadmium and nickel into the air each year,,
I guess used oil poses similar problems.
About a decade or so ago, some heating oil company (in NY,, I believe) was dumping used motor oil into the heating oil,, and selling it.
The heating oil company was being paid a disposal fee,, then turning around and selling the oil as heating oil.
I would bet that you could add 5% or 10% used oil to fuel oil,, and it would burn perfectly.
IIRC,, there was jail-time involved when those guys got caught.