Yamalube 5W-30 4-Stroke Synthetic Marine Oil Yamalube 5W-30 is a fully synthetic FC-W NMMA certified marine oil designed for 4 stroke engines. This high performance oil is designed to help push your performance by increasing lubrication and decreasing friction between parts. By decreasing the amount of friction Yamalube engine oil helps promote efficient fuel economy. Specific marine additives combat rust, corrosion, varnish, and wear while also providing high levels of bearing protection, resis