JASO

Japanese Automobile Standard Organization (JASO)

In Japan, it has been common practice to use the API Service Classification Standard for quality assurance of automotive diesel engine lubricants products. However, it has been discovered that the API Service Classification Standards are not always applicable to diesel engines designed and manufactured in Japan, due to differences in design between Japan and North American engine manufacturers. More specifically, in a majority of diesel engine lubricants in wide use in Japan, special performance characteristics such as wear prevention improvement characteristics for sliding rocker-arm valve train are added so that the requirements for made-in-Japan engines are satisfied. Furthermore, automotive manufacturers in Japan have requested the establishment of new engine lubricant quality standards that will meet the recent requirements surrounding exhaust emission regulations, and the need for engine lubricants to comply with vehicle emission systems.

Engine oils subject to the Automotive Diesel Engine Oil Standard JASO M 355 shall be classified into one of three categories: DH-1, DH-2, or DL-1, all of which apply to four-cycle diesel engines.

DH-1
This classification has been developed for the diesel engines which are subjected to long-term exhaust emission regulations, and stipulate requirements for performance in such conditions as wear prevention, corrosion prevention, high-temperature oxidation stability, and soot control. Further, engine lubricants conforming to DH-1 standard (hereinafter) DH-1 Oils) are intended for suppressing deterioration of piston detergency, formation of deposits at high temperature, foaming, oil consumption due to evaporative loss, viscosity decrease by shear, deterioration of oil seals, etc.

DH-1 Oils are also applicable to engines which were predating the long-term exhaust emission regulations. Based on the premise that the drain intervals recommended specified by engine manufacturers are observed, application of a DH-1 Oil is also allowed in cases where diesel fuel having more than 0.05% sulfur content used.

DH-2
This classification has been developed for the heavy-duty diesel engines which are equipped with after-treatment devices such as Diesel Particulate Filter (DPF) and catalyst in compliance with exhaust emission regulations subsequent to the new short-term regulations. Engine Lubricants conforming to these standards (hereinafter “DH-2 Oils”) have an excellent applicability to DPF and catalyst while keeping the same performance level as required for DH-1 classification. DH-2 Oils can be used only in the environment where low-sulfur diesel fuel having not more than 0.005% sulfur content is used.

Based on the premises that low-sulfur diesel fuel having not more than 0.005% sulfur content is used and that the user complies with oil change intervals recommended by the engine manufacturer, application of a DH-2 Oil is also suitable for use in engines predating the new short-term exhaust emission regulations.

DL-1
This classification has been developed for the light-duty diesel engines which are equipped with after-treatment devices such as Diesel Particulate Filter (DPF) and catalyst in compliance with exhaust emission regulations subsequent to the new short-term regulations. Engine lubricants conforming to these standards (hereinafter “DL-1 Oils”) have an excellent applicability to DPF and catalyst while keeping the same performance level as required for DH-1 classification. DL-1 Oils can be used only in the environment where low-sulfur diesel fuel having not more than 0.005% sulfur content is used.