JASO Performance specifications for motor vehicle engine oils
These specifications were developed by the Japanese Automotive Standard Organization (JASO) and concern motorcycle engine oils. JASO T903 standard refers to oils for 4-stroke engine vehicles and JASO M345 standard refers to oils for 2-stroke engine vehicles.
Standard JASO T903 establishes globally recognized requirements for oils for 4-stroke motorcycles. It defines the performance level of motorcycle oil for various motorcycle designs. The classification system measures several characteristics, including motorcycle oil’s resistance to clutch (or slip) slippage and protection against engine wear and gearbox pitting.
JASO 4-stroke Motorcycle Engine Oil Classification
| Specification | Description |
| MA | Standard category for oils used in the same lubrication system (engine, clutch and gearbox use the same oil). JASO MA oils do not contain friction modifiers. |
| MA1 | The category is designed for 4-stroke motorcycles and scooters and is primarily suitable for engines with a wet clutch. |
| MA2 | The oil category provides a higher clutch friction efficiency. JASO MA2 oil is ideal for motorcycles with a catalytic converter. |
| MB | This category is for motorcycles that use separate oils for engine, clutch and gearbox. JASO MB oils are generally designed for reliable, low-friction clutch engines and provide improved fuel economy for use in dry clutch engines (e.g. scooter engines). |
JASO M345 standard specifies requirements for oils for 2-stroke engines. JASO specifications evaluate the performance of oils, primarily on the criteria of engine cleanliness, lubricity, and the impact on the exhaust system.
JASO Classification of 2-stroke engine oils
| Specification | Description |
| FA | The lowest specification for 2-stroke motorcycle oils. It was the original standard set to regulate lubricity, starting torque, detergency, exhaust smoke cleanliness and exhaust system blockage. It was made outdated in 2005. |
| FB | Defined mainly for high lubricity oils without any requirements for exhaust cleanliness and exhaust system blockage. |
| FC | Has the same testing levels as JASO FB for lubricity and initial torque. However, it is higher than JASO FB in terms of exhaust gas and exhaust system blocking standards. |
| FD | The specification is intended for oils with higher efficiency of detergent properties and engine cleanliness, as well as meeting the requirements for lubrication and emissions. Oils with JASO FD rating outperform both JASO FB and JASO FC oils in all evaluated criteria. |
Note
For complete and up-to-date information on JASO requirements for engine oils for motorcycles please visit: www.jalos.or.jp