I've inherited a 2003 carolina skiff 16DLX with a 40HP Yamaha 2 stroke (3YMXM.6981GA). The engine has an oil tank for 2 cycle oil. The gas that was in the tanks was a mix. I was under the impression that the gas should not be mixed. The oil is injected from the oil tank. Is that a correct assumption? If so, should I do anything other than changing the fuel over i.e. drain the carbs, filters etc.?