JASO M345 is a quality classification standard for two stroke engine oils for engines of Japanese origin. It was introduced by the Japanese Automotive Standards Organization (JASO) in 1994 as JASO M345-93 with the quality levels JASO FA, JASO FB and JASO FC – with FC setting the highest standard. It was revised in 2004 as JASO M345:2004 which discontinued the FA level, and introduced the new JASO FD level – the FD level supersedes JASO FC as the highest rating.
The different quality levels set requirements with regard to properties such as minimum lubrication, minimum detergency, maximum smoke and maximum deposits. A two stroke engine oil is granted the official JASO seal if it has been independently tested. The seal is a rectangle; in the upper quarter of the rectangle will be a serial number, and the lower three quarters will just have the letters FB, FC or FD.
JASO FA – original spec established regulating lubricity, detergency, initial torque, exhaust smoke and exhaust system blocking.
JASO FB – improved requirements over FA with regard to lubricity, detergency, exhaust smoke and exhaust system blocking.
JASO FC – lubricity and initial torque requirements same as FB, however far higher requirements over FB with regard to detergency, exhaust smoke and exhaust system blocking.
JASO FD - same as FC, except with far higher detergency requirement.
- "Two-stroke motorcycle oils - JASO M345 standard". www.mceo.com. The Lubrizol Corporation. Retrieved 21 October 2013.