I fail to see the point. A well-built, well-maintained automotive engine will run 200,000 miles without any oil in the gas. What would you expect to improve? OTOH, I could imagine a lot of carbon buildup in the cylinders and on the valves, not to mention the potential damage to the cats, by adding oil that's not supposed to be there.
All in all, it's not such a great idea.
All in all, it's not such a great idea.