New JASO Diesel Wear Test Adopted


The Japanese Society of Automotive Engineers recently adopted a valve train wear test for diesel engine oils that ends reliance on a test motor no longer in circulation and reference oils that were also running out.

The new test, JASO M354:2015, runs on a Hino Motors engine, N04C, that meets Japans latest air pollution emissions standard. JASO wrote the valve train wear test so that it can be run on the same engine and at the same time as a year-old piston detergency test, a cost-saving move for engine oil formulators.

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The JASO Diesel Engine Oil Standard, JASO M355, is recommended by Japans main manufacturers of heavy-duty trucks – Hino, Mitsubishi Fuso and UD Trucks – for operators in Japan as well as other markets. As such, the specification is widely followed throughout much of Asia.

The valve train wear test is one of four engine tests in JASO M355, which also includes 11 bench tests. The valve train test is the specifications gauge of an engine oils ability to protect against wear as the engine becomes loaded with soot – a growing issue since one of the most popular methods of reducing exhaust emissions of soot collects and dumps the particles into the engine oil.

For 16 years the test was run on a Mitsubishi Fuso 4D34T4 motor that is no longer manufactured, so test labs would eventually run out of them. There were also problems with two of the reference engine oils used to calibrate the test engines, referred to as DV1 and DV2. Production of DV1 had ceased, as had production of the additives used to make DV2.

Hinos Kenji Tomizawa, chairman of the JASO Diesel Engine Oil Standard Revision Task Force, said the new test also has the advantage of catching up to air emission control standards that have tightened since the old Mitsubishi Fuso motor was put into use.

The task force consists of 12 companies working in a format developed by the Japan Automobile Manufacturers Association in cooperation with the Petroleum Association of Japan, Engine Oil Subcommittee and the Japanese Lubricating Oil Society (JALOS). The Participants fall into three groups – automobile manufacturers, oil suppliers and additive companies.

JSAE adopted the new M354:2015 in April. In May JALOS posted an announcement about the adoption on the English version of its website.

JASO M354:2015 gauges an oils ability to prevent soot-related wear by installing the oil into a test engine and running the engine for 200 hours. As the engine runs, the level of carbon residue in the oil sump increases, and the procedure requires it to reach at least 3.0 percent of the oils mass by the time the test ends. The lab running the test then measures the tappet wear.

The previous valve train test ran for 160 hours and had to be run by itself. The task force that developed the new wear test was able to devise it to run simultaneously with detergency test JASO M336, which was updated last year. Thats a meaningful accomplishment for the lubricant industry, because engine tests are the most expensive part of getting an oil approved.

Developing tests that can run together is significant because oil development cost is expected to be reduced, Tomizawa said. He noted that the JASO M354 and JASO M336 updates were part of a three-phase undertaking, now three years old, to update the diesel oil standards. The final phase, now underway, is to develop a test procedure of the fuel efficiency performance of the oil that will be added to the standard.

Tomizawa noted that the task force tested commercially available oils that pass the old wear test and found that they pass the new test, too.

In addition to choosing the new engine and procedures for the test, the task force had to set test limits and develop reference oils that are used to calibrate test engines. The new test, JASO M354:2015, uses reference oils DV3 and DV4 instead of DV1 and DV2.