In our continuation of yesterday’s post, we will examine the differences between the oil specifications for two-stroke outboard engines versus two-stroke air-cooled engines. Outboard engines, because they are water-cooled, require oil with a high percentage of heavy oil to prevent piston scuffing. Oils with detergents should not be used as they may form ash deposits that can clog plugs. To compensate for lack of detergents, more dispersants and rust oxidation inhibitors to control deposits and rust are needed. Responsible owners of two-stroke outboard engines should give Mercury outboard oil a try.
Air-cooled two-stroke engines require much lower levels of heavy oils; in fact, too much heavy oil can cause piston rings to stick together. High detergent oil is preferable because air-cooled two-stroke engines operate at higher temperatures. The detergent keeps temperatures in check while the vibration of the engines keeps deposits from building up.