Japanese Automotive Standards Organization. The primary automotive standards organization in Japan. JASO was created to better address the unique specification needs of Japanese engines. MB oils are formulated to deliver low clutch frictional performance. The intent of the specification is to provide enhanced fuel economy performance for non-wet clutch applications. These applications generally use external centrifugal clutches and Continuously Variable Transmissions (CVTs); for example: scooters.
The main physical, chemical and clutch frictional requirements, according to the current version of the standard (JASO T903:2016), for JASO MB oils are shown below:
Physical and Chemical
|A product of the combustion of metals commonly found in detergents. As a lubricant property, sulfated ash content is a measure of metal content (usually Zinc, Calcium, and Magnesium) and allows formulators to stay within specified limits in order to minimize the negative effects of abrasive ash particles. Sulfated ash is determined by charring the oil, treating the residue with sulfuric acid, and evaporating to dryness, the result being expressed as % by mass.||D874/JIS K 2272||% mass||1.2 max.|
|Phosphorus||D4951/JPI-5S-38||% mass||≥0.08 and ≤0.12|
|Foaming Tendency (foaming/settling)|
D892/JIS K 2518
|Sequence II||mL||50/0 max.|
|Sequence III||mL||10/0 max.|
|Evaporation Loss (NOACK)||% mass||20 max.|
(The measurement of a fluid's resistance to flow under the force of gravity at a specific temperature, usually 40°C or 100°C. (100°C) after test)
xW-30 : 9.0 min.
xW-40 : 12.0 min.
xW-50 : 15.0 min.
Others : Stay in grade
|High Temperature High Shear (High Temperature High Shear. A measure of a fluid’s resistance to flow under conditions resembling highly-loaded journal bearings in fired internal combustion engines, typically 1 million s–1 at 150°C.) A measure of a fluid's resistance to flow. A fluid with a higher viscosity flows less easily.||American Society for Testing and Materials. An organization that develops international standards for industry, including test methods, specifications, and best practices. Many tests that certify a lubricant to a specification are overseen by ASTM. D62781||mPas||2.9 min.|
Note 1 : Test shall be conducted by diesel injector method using the standard test conditions (30 cycles)
Clutch Test The resistance to motion of one object over another. Friction depends on the smoothness of the contacting surfaces, as well as the force with which they are pressed together. Properties (JASO T 903:2016(Annex A))
|Dynamic Friction Index (DFI)||≥0.40 and ≤1.35|
|Static Friction Index (SFI)||≥0.40 and ≤1.45|
|Stop Time Index (STI)||≥0.40 and ≤1.40|
Note : MB shall be within the MB range for each of the three indices (DFI, SFI, and STI), or two indices shall be in the MB range and one index shall be in the MA range, or one index shall be in the MB range and two indices shall be within the MA range.
Submitter may On-File register an oil which satisfies the MB specification when one or more of the indices conform to the MB limits.
The significance of the indices:
|Dynamic Friction Index (DFI)||Measure of clutch feel and how progressively power transfers during clutch engagement|
|Static Friction Index (SFI)||Measure of closed clutch pack torque handling capacity – resistance to clutch slip under high-torque “break-away” conditions|
|Stop Time Index (STI)||Measure of how quickly the clutch engages|
For more information on JASO MB, contact your Lubrizol representative.