2-Cycle Engine Oil vs. Outboard Engine Oil
Posted by David Schatz, Owner - DHS Equipment on Nov 13th 2014
A frequent question we answer at DHS Equipment, is about oil for 2-cycle engines. Many people ask, "can I use outboard engine oil in my 2-cycle equipment?" This has been debatable for years, but the short answer is, no, you should not.
Think about this: the main difference between 2-cycle outboard engines and 2-cycle power equipment engines is how they're used. An outboard engine on a boat is typically accelerated to a particular RPM, which maintained until you've reached your destination. (Typically half the RPM of a chainsaw or concrete saw.) The engine on a 2-cycle chainsaw or concrete saw is constantly stopped and started, alternating between periods of idle and periods of redline RPM's, upwards of 14,000 RPM!
Another point to consider, is that outboard engines are typically water-cooled and have a constant flow of fresh coolant which is not recirculated. This means that overall engine temperature is much lower than that of an air-cooled 2-cycle engine found in a chainsaw.
Water-cooled outboard engines require a heavy oil to prevent piston scuffing. In addition, oils containing detergents should not be used in an outboard engine, as the detergents may form ash deposits in the cylinders and foul spark plugs. Since outboard engine oils don't include detergents found in 2-cycle outdoor power equipment oil, they require a high amount of dispersants, rust, and oxidation inhibitors to control deposits and rust.
Air-cooled 2-cycle oil for outdoor power equipment require less heavy oils, which can cause piston ring sticking and loss of power. Due to operating conditions and temperature, a high detergent formula is used, which provides deposit control under high temperature use, unlike outboard engine oil. High detergent oil provides necessary protection from high RPM, high engine temperature operation and engine damage.
As you can see, there is a major difference between outboard engine oil and 2-cycle oil for power equipment. By using outboard engine oil in your power equipment, you're only doing harmful damage to your engine. Always use an oil meeting the American Petroleum Institute (API) service classification TC, which is the best oil for 2-cycle, air-cooled engines.