JASO (Japanese Automotive Standards Organization) is a standard for lubricants used in Japan. The basis for the development of this standard was the growing requirements for motor oils and their impact on the environment. This issue became especially acute for Japanese manufacturers, due to the rapid tightening of product requirements by environmentalists. In addition, Japanese engineers noted other reasons that necessitated the creation of their own classification:
- high degree of wear of valve mechanism parts of diesel engines of automobiles when using oils with a high content of dispersants (especially in oils that meet the requirements of the American specification API CG-4);
- high-temperature deposits on pistons. As a rule, the upper ring in modern Japanese engines is located lower than in European and North American engines, as a result of which the maximum temperatures in the area of the upper piston rings are significantly lower;
- the spread of Japanese engines with the EGR (Exhaust Gas Recirculation) system — an exhaust gas recirculation system that allows the remaining fuel in the exhaust gases to be burned. EGR contributes to the growth of acidity in engine oil, which can lead to significant corrosion of surfaces inside the engine. The classification also covers motor oils for two-stroke engines.
In JASO standards, all motor oils are divided into three major categories.
4-stroke engines of motorcycles and gasoline cars
- MB – oils with a low friction coefficient. Not suitable for motorcycles with wet clutches.
- MA-1 – average oil in this classification by friction coefficient. Suitable for motorcycles with wet clutch and low load.
- MA-2 – oil with the highest coefficient of friction. Ideal for sports motorcycles and heavy loads.
For diesel engines
Diesel engines are most susceptible to soot formation, oxidation, corrosion. This JASO class is aimed at standardizing these effects.
- DH-1 is probably the most popular standard due to its advantages (wear prevention; corrosion prevention; stability to high-temperature oxidation; reduction of soot formation). Suitable for diesel engines that meet long-term exhaust emission standards. Recommended for use if the sulfur content in diesel fuel is higher than 0.005%.
- DH-2 - for use in commercial vehicles and special equipment under heavy load conditions. Designed for engines with preliminary cleaning of exhaust gases (DPF filters and catalytic converters). For refueling a car with diesel fuel, the sulfur content of which is less than 0.005%.
- DL-1 - for small and other cars, operating in light and moderate operating conditions and having preliminary cleaning of exhaust gases. For fuel with a sulfur content below 0.005%.
For 2-stroke engines of motorcycles and cars
- FD - Smokeless oils for two-stroke engines of motorcycles and other machines with improved engine cleanliness characteristics in comparison with JASO FC, meet the highest requirements for use in Japan.
- FC - Smokeless oils for two-stroke engines of motorcycles and other machines, meeting the basic requirements for use in Japan.
- FB - Oils for two-stroke engines of motorcycles and other machines that meet the minimum requirements for use in Japan.
- FA - Oils for two-stroke engines of motorcycles and other machines intended for use in developing countries.