[nevadatim]

Just bought this from private seller, no owners manual came with it. How often should I change the oil? What other routine service is required?
Thanks.

[Laddies]

There is no crankcase oil in that engine, go to the mercury marine site and get a manual quickly

[Silvertip]

As Laddies said, two stroke engines do not have oil in the crankcase. That's why oil injection systems are used or else oil is mixed with the fuel to provide lubrication as it passes through the engine. This engine will be very short lived if you don't understand the principle of a two-stroke motor. Routine service consists of changing the oil in the lower unit (the bulge where the prop lives) once a year. Chech/change the spark plugs annually or as needed. Use fuel stabilizer if the engine is not used regularly.