JASO Oil Specifications

JASO Oil 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.

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.

JASO MA

Japanese standard for special oil which can be used in 4-stroke motorcycle engine with one oil system for engine, gearbox and wet clutch system. Fluid is non-friction modified.

JASO MB

MB grade oils are classified as the lowest friction oils among motorcycle four-cycle oils. Not to be used where a JASO MA grade oil is required.

Modern motorcycles usually have the same oil lubricating the engine and the wet clutch. For this purpose most of the time the regular friction modified engine oils are not good enough. To make sure that the right oil is used motorcycle manufacturers usually require the oil to meet one of the JASO standards explained below.

The motor oils that meet the JASO T 903:2006 standard can be classified into four grades: JASO MA, JASO MA1, JASO MA2 and JASO MB. The classification is based on the results of the JASO T 904:2006 clutch system firction test.

In order for a motor oil to meet any of the above mentioned JASO standards it must be at least of one of the following quality levels:

• API SG, SH, SJ, SL, SM
• ILSAC GF-1, GF-2, GF-3
• ACEA A1/B1, A3/B3, A3/B4, A5/B5, C2, C3

Furthermore, the motor oil's Dynamic Friction Characteristic Index (DFI), Static Friction Characteristic Index (SFI) and Stop Time Index (STI) should be within the following limits according to the JASO 904:2006 friction test:

	JASO MA	JASO MB
Dynamic Friction Characteristic Index (DFI)	≥1.45 and <2.5	≥0.5 and <1.45
Static Friction Characteristic Index (SFI)	≥1.15 and <2.5	≥0.5 and <1.15
Stop Time Index (STI)	≥1.55 and <2.5	≥0.5 and <1.55

The JASO MA range is further divided into 2 distinct ranges - the JASO MA1 and JASO MA2 ranges - as follows:

	JASO MA1	JASO MA2
Dynamic Friction Characteristic Index (DFI)	≥1.45 and <1.8	≥1.8 and <2.5
Static Friction Characteristic Index (SFI)	≥1.15 and <1.7	≥1.7 and <2.5
Stop Time Index (STI)	≥1.55 and <1.9	≥1.9 and <2.5

If all three properties of a JASO MA oil fall within the limits specified as MA1 then the oil can be classified as a JASO MA1 oil. If all its properties fall within the limits of MA2 then it can be classified as a JASO MA2 oil. If some properties fall within the MA1 subcategory but others in MA2 then the product is simply a JASO MA product.

link: http://www.oilspecifications.org/jaso.php