JASO Oil Specifications

2T specifications

Japeneese motorcycle manufacturers found the limits demanded by the API TC specifications too loose. Oils meeting the API TC standard still produced excessive smoke and could not prevent exhaust blocking. Therefore the Japanese Engine Oil Standards Implementation Panel (JASO) introduced the following specifications:

JASO FA

Original spec established regulating lubricity, detergency, initial torque, exhaust smoke and exhaust system blocking.

JASO FB

Increased lubricity, detergency, exhaust smoke and exhaust system blocking requirements over FA.

JASO FC

Lubricity and initial torque requirements same as FB, however far higher detergency, exhaust smoke and exhaust system blocking requirements over FB.

JASO FD

Same as FC with far higher detergency requirement.

Find out more about JASO's 2T specifications from their website.

4T specifications

Modern passenger car engine oils contain more and more friction modifiers. While this is the good thing for those segments (reduces wear and fuel consumption) it's bad for the motorcycles. At least for those motorcycles which use engine oil to lubricate their transmission and wet clutch. JASO introduced the MA and MB specification to distinguish between friction modified and non friction modified engine oils. Most four-stroke motorcycles with wet clutches need a JASO MA oil.