Four stroke outboard engines often have long periods of idle, and in cooler water the oil can accumulate enough fuel which then dilutes the viscosity which may lead to excess wear.

"Automotive additive packages in API SJ oils, which is the category currently recommended for most of today's marine four stroke engines, can handle the oil dilution issue. But with the looming possibility of substantial reductions in the percentage of ZDDP in future automotive engine oil categories, marine applications may be placed at risk,” Don Schultze, NMMA, said.

This has lead to the development of the specification of the first Marine Four Stroke Outboard Oil.