I doubt that it would make a noticeable difference, though the small amounts of Shell "friction reducing additive" may lead one to think so. The part about Stoddard solvent bothers me a bit. You have to wonder what that might do to the windings in the fuel pump. Gasoline manufactures have quite a few things to consider when selling their products. One of them is IVD or Intake Valve Deposits. Mandated by the govt. and not a good idea to ignore. Adding 2 cycle oil to the gas may defeat the detergency of the gas additives and cause EGR failures as well. It may also cause the car to fail smog tests, either in the short term, from the oil itself, or due to the long term effects on other "systems".