there is a huge difference in cheap oil and main brand brand oil. i cant tell you the chemical break down but what i can tell you from my years of experience as an outboard tech cheap oil does not burn half as well as premium brand oils. side effects of cheap oil is plugged exhaust systems, increased spark plug fouling, bad lubricating through out the rpm range. most cheap 2 stroke oils are really designed for your weedeater that you run at a constant full throttle, not for sustained time at an idle. doesnt matter what kind of motor i own i will run quicksilver or mercury premium plus, or d.f.i. oil.