JASO Upgrades Diesel Oil Spec


SINGAPORE – An upgraded standard for diesel engine oils will be released in Japan next week, armed with a newly viable test for piston detergency. Later this year, the Japanese Automotive Standards Organization also hopes to upgrade the specifications test for valvetrain wear.

Hino Motors Kenji Tomizawa reported on the progress March 6 at the Fuels & Lubes Asia Conference here. JASOs specification for diesel engine oils includes a test for piston detergency, M336, and Tomizawa said it had grown out of date. The M336 was adopted more than 15 years ago, and has been performed on the TD25 test engine, which is no longer available. The same was true of the reference engine oils prescribed for the test.

A JASO task force selected a new test engine, Hinos N04C, and developed updated reference oils. It also switched methods for measuring results from the Top Groove Fill to Weighted Total Demerits. Tomizawa said the WTD method is more appropriate at the higher temperatures prevalent since automakers down-sized engines in search of better fuel economy.

JASO is already working on a revision to M354, the valvetrain wear test. Like the M336, the M354 needs a new test engine and reference oils, Tomizawa said. The standards organization also has additional work on its plate – primarily development of a fuel economy test.

The task force has also been discussing [development of] a fuel economy oil performance test method in view of the trends with API and ACEA standards, he said. API and ACEA engine oil specifications are developed in North America and Europe, respectively.

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