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In order to meet the U.S. EPA's 2007 on-highway emission standards for particulate and NOx, all diesel engines will require diesel particulate fi lters (DPFs) and cooled exhaust gas recirculation (EGR) and will utilize ultra-low sulfur fuel. As this will be the fi rst time that all on-highway diesel engines will employ DPFs combined with ultra-low-sulfur fuel, the Engine Manufacturers Association (EMA) requested that a new oil category be developed to provide compatibility with DPFs in the exhaust system, as well as engine durability for both new and pre-2007 engines. This paper reviews the development of this new oil category called API CJ-4, which was introduced in October 2006. This diesel engine oil category is the fi rst in the U.S. which limits the oil's sulfated ash, phosphorus, and sulfur in order to insure adequate service life of the DPF. The API CJ-4 oil category includes 9 fired engine tests and 6 bench tests.

In order to meet the U.S. EPA's 2007 on-highway emission standards for particulate and NOx, all diesel engines will require diesel particulate fi lters (DPFs) and cooled exhaust gas recirculation (EGR) and will utilize ultra-low sulfur fuel. As this will be the first time that all on-highway diesel engines will employ DPFs combined with ultra-low-sulfur fuel, the Engine Manufacturers Association (EMA) requested that a new oil category be developed to provide compatibility with DPFs in the exhaust system, as well as engine durability for both new and legacy engines. This paper reviews the development of this new oil category called API CJ-4, which will be introduced in October 2006. This diesel engine oil category is the first in the U.S. which limits the oil's sulfated ash, phosphorus, and sulfur in order to insure adequate service life of the DPF. The API CJ-4 oil category includes 9 fi red engine tests and 6 bench tests.

Of all the performance tests in the current International Lubricant Standardization and Approval Committee (ILSAC) GF-3 and GF-4 categories, the Sequence IIIF and Sequence IIIG are among the most difficult for the formulator. The Sequence III engine dynamometer tests place a premium on oxidation, high-temperature deposits, and valve train wear control. Besides appearing in the North American Passenger Car Motor Oil (PCMO) specifications, the Sequence III is required for European gasoline engine oils, for American Petroleum Institute (API) diesel engine oil categories, and for base oil interchanges (BOI) among licensed engine oils. The ability to screen antioxidants for the Sequence III is of special interest for developers of engine oil technology. Antioxidants are the single most expensive component and the search for cost-effective oxidation control is among the top technical hurdles for the North American PCMO categories.

Fleet customers demand reduced operating costs. This necessitates the development of engine oils which can provide maximum fuel economy and extended oil drains, while still maintaining engine durability. This is particularly important in diesel engines produced since October 1998. These engines use retarded timing to meet EPA's emission requirements and, as a consequence in some cases, generate high soot levels in the engine oil. Extended oil drains in 1995 Caterpillar 3406E and 1996 Detroit Diesel Series 60 engines found no statistical difference in fuel economy or wear between a synthetic SAE 5W-40 and an SAE 15W-40 using API Group II base stocks. Both oils had the same API CG-4/SJ quality level. Soot levels at oil drains of 40,000-50,000 miles (64,372 - 80,465 km) ranged from 0.5-1.2%.

Higher soot levels in the crankcase oil may be an unavoidable result of lower exhaust-emissions. This study demonstrates that high soot levels in the oil can be dispersed, viscosity increases minimized, and filter plugging prevented by selecting the proper type of ashless dispersant and V.I. improver.