I have heard tell of a gentelman who is running a little sunflower oil in his tank. He is powering all his diesel farm machinery with sunflower oil, which he grows and presses on his farm. He adds a little to his gas vehicles also, about 1 pint per 18-20 gallons if I recall correctly. He claims 3-4 MPG increase on a jeep cherokee, but I can neither confirm nor deny this. He mixes a little Regular Unleaded Gas(RUG) with his freshly squeezed sunflower oil to break it down and direct burn it in his diesels. If I recall correctly, he is using only enough RUG to get the veg oil into the same viscosity neighborhood as #2 diesel. Apparently this is a method gaining favor with the folks running straight veg oil. The RUG breaks up the longer molecule chains and helps the oil spray/atomize better in an injector, and can eliminate the need to preheat the straight veg oil. This guy dosn't preheat any of his veg oil fueled engines. I havn't tried this yet, as I have no virgin sunflower oil to test with. Anything that adds BTU content to the fuel should improve mileage.
YMMV...
2 cycle oil is designed to pass thru fuel systems, and combust cleanly, so I doubt it would hurt anything up to a certain point. I guess it would depend on what ratio you are running. Of course over oiling may effect the exhaust system components such as a catalytic converter. One of my 2 stroke street bikes had cat converters in the pipes, and it handled the 2 cycle exhaust OK.
Good luck