Yamalube 10W-30 4-Stroke Conventional Marine Oil Yamalube 10W-30 is designed for maintaining viscosity in 4 stroke outboard engines in marine environments. NMMA FC-W certified, this oil features rust inhibitors that help keep you moving smoothly and increase engine life. Yamalube 4M utilizes anti-friction protection to help promote efficient fuel economy and increased performance. Additionally, Yamalube 4 Stroke Oil has been formulated with the best blend of anti-foam technology available. Oil f