Bel-Ray® Friction Modified Thumper Racing 4T Engine Oil is a 4-stroke motorcycle racing oil formulated specifically for motorcycle applications using separate engines and transmissions. Friction modifiers reduce engine temperature, increase horsepower and extend engine life. Meets API SM and JASO MB requirements. Suitable for air-cooled/liquid-cooled 4-stroke engines. DO NOT USE IN WET CLUTCH APPLICATIONS.