Water cooling is widely used in outboard motors for boats, unlike most engines in other applications which are air-cooled or close circuit liquid-cooled. Outboard engines, due to their cooling design and operating conditions, require specialised oils which differ from common two-stroke motor oils. Major performance requirements for two-stroke engines include protection against piston and cylinder scuffing, protection against ring-sticking and exhaust blocking, smoke reduction and corrosion prevention. For outboard engines, oil performance is classified according to NMMA. Your local BP office will assist you in finding the BP product to suit your needs.