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. The new multi-cylinder tests in the category include Caterpillar C13, Cummins ISB, Cummins ISM, Mack T-12, and Mack T-11, which cover oil consumption, piston deposits, ring-liner, bearing wear, valve-train wear, soot dispersancy, oil oxidation, and viscosity shear. These tests are juxtaposed on existing tests selected from the API CI-4 category. It is the most robust API oil category ever developed in the U.S.