Emission regulations in California typically require exhaust treatment with a 3-way catalyst to achieve emission standards for inboard boat engines. The relevant legislation of EPA (Environmental Protection Agency) comes also into effect for Sea-Doo Sport Boats with the engine model year 2013. The lube oil consumption (LOC) of the engine has a decisive influence on the durability of a 3-way catalyst. Sustained, an excessively high oil consumption damages the sensitive surface of the catalyst wash coat and leads to a rapid deterioration of the catalyst conversion rate because of “poisoning” with oil ash. As a way to reduce the lube oil consumption of a combustion engine, the Air Plasma Spray (APS) coating of the cylinder bore was implemented as part of an engine development project.