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An oxidation catalyst for diesel engines has been tested in the North American market with proven satisfactory initial performance and durability tests of vehicles but has yet to be evaluated by its bench durability tests due to shorter test duration. Therefore, the oxidation catalyst, durability tested by vehicle and bench, was subjected and the test data were analyzed to clarify its degradation mechanism and set up outlooks for evaluation of its durability by bench tests.

This paper reviews the development of a new standard for four-stroke diesel engine oils, JASO DH-1 (JASO M355: 2000). This standard was introduced to the market on April 1, 2001. It prescribes the minimum performance for engine oils conforming to four-stroke diesel engines manufactured by Japanese OEMs. This standard is composed of four engine tests and seven bench tests. The engine tests include a piston detergency test (JASO M336: 1998), valve train wear test (JASO M354: 1999), soot dispersancy test (ASTM D 5967-99) and high temperature antioxidation test (ASTM D 5533-97a). The piston detergency test and the valve train wear test were developed in Japan. The bench tests measure hot surface deposits, anti-forming, volatility, anti-corrosion, shear-stability, total base number, and seal compatibility.

In this study, the oxidation stability, soot dispersancy, antiwear performance, and friction-reducing capability of friction modifiers (FMs) were evaluated, and an SAE 5W-30 fully synthetic oil with MoDTC type FMs was developed for heavy-duty diesel engines. In several engine tests, it was confirmed that the developed oil can double the oil drain interval in comparison with API CD SAE 30, even when EGR is applied, and improves the fuel efficiency.