To understand how two cycle oil works in your engine, we need to cover some basic information on engine operating conditions and oil formulation. Outboard engines are characterized by their constant speed, high output operation. They are usually set at a desired high speed and continue at that speed until the destination is reached and then throttled down. Also, they are constantly cooled with fresh, cool, non re-circulated water.
Chainsaws, on the other hand, are a high action operation. They are constantly started and stopped, used for short periods, and frequent overloads are its hard place in life. Additionally, they have smaller displacements than outboards and are air cooled. By understanding how the operation of an engine can affect the oil used and how oil can affect the engine, we can better appreciate the difference between a water cooled two-cycle oil and one formulated for an air cooled two-cycle engine.