Today’s modern high performance motorcycle engines demand much more from an oil. Only the very best fully synthetic oils will protect your engine properly. The advanced formula used in Rock Oil Synthesis 4 has been specifically developed to provide the ultimate protection whilst releasing maximum power from an engine Synthesis 4 10w40 is a fully synthetic lubricant combining the latest synthetic bases with advanced additive technology to give outstanding performance. Rock Oil Synthesis 4 10w40 is approved to the highest Japanese engine specification, JASO MA2, allowing safe, predictable use in wet clutch applications