The best way to find out when and how often to perform maintenance is to follow your engine manufacturer's maintenance schedule. This may include a schedule for the various parts of the engine. It will also give you a good idea of how often you should change the oil. A marine engine will need a full service every few hundred hours of use. Depending on your engine model, you may also need to flush the cooling system with antifreeze to prevent freezing.If you own a diesel engine, you'll need to do some special maintenance For more details kindly visit here outboardrebuildingtips.wordpress.com/2022/12/08/engine-servicing-and-maintenance-for-boat-owners/