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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.

Modern Passenger Car Motor Oils (PCMOs) are formulated to provide superior wear, oxidation, and deposit control under the most demanding driving conditions. In most PCMOs, zinc dialkyldithiophosphate (ZnDTP) has been the dominant antiwear and antioxidant agent for well over 50 years. Unfortunately, the phosphorus in ZnDTP may partially deactivate the exhaust emission catalyst. To ensure that the catalysts function for at least 120,000 miles, engine manufacturers are exploring phosphorus limitations for upcoming PCMO performance categories. This paper explores the antiwear film formation of low phosphorus engine oils using the Electrical Contact Resistance bench test. A prototype ILSAC GF-4 formulation blended with varying amounts and types of ZnDTP was tested at temperatures typical of operating engines. Secondary ZnDTP was found to produce the best films under the broadest temperature range.

Because of the rising costs of engine tests, bench testing is a necessity in engine oil development. Which bench test to use remains a problem. Recently, we have reported on the use of electrical contact resistance (ECR) coupled with a ball-on-disk tribometer to study the formation and the durability of antiwear films from binary additive mixtures. This paper extends the ECR study to fully formulated fresh oils run in both fired gasoline engines and the ECR bench test. X-ray Photoelectron Spectroscopy (XPS) analyses of used Sequence VE engine parts from highash fully formulated lubricants are shown and the relationship of ECR film formation to fired-engine test performance is discussed.

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%.

In order to meet EPA's emission requirements for 1999 diesel engines, soot levels in the crankcase oil will increase significantly due to retarded timing to lower NOx. This study uses the Cummins M11 engine at soot levels up to 9% in the crankcase oil to demonstrate how oils can be formulated to prevent valve train wear, extend filter life, and maintain oil pumpability. The study includes the oil formulation development and the evaluation of API CG-4/SJ oils at 4.5% soot and API CH-4/SJ oils at 9% soot. In addition it includes X-Ray Photoelectron Spectroscopy (XPS) for surface film analysis and Surface Optical Profilometry and Scanning Electron Microscopy (SEM) of the valve train valve-bridges and rocker pads to determine the mechanism of failure. The oil's low temperature rheology as it affects oil pumpability is defined by Mini Rotary Viscometer (MRV TP-1), Scanning Brookfield Test (SBT), and Cold Cranking Simulator (CCS).

The Nissan KA24E engine test is designated to replace the Ford Sequence VE engine test as the low temperature valve train wear requirement for ILSAC (International Lubricant Standardization and Approval Committee) GF-3. The KA24E (recently designated the Sequence IV A) represents much of the current world-wide material and design technology while retaining the sliding cam/follower contact found in earlier engine designs. The work presented here is the first of two reports. In this first report, the physical and chemical environment the KA24E engine presents a lubricant is characterized and compared to those of the Sequence VE engine. Valve train materials and wear modes are investigated and described. Although chemical analysis of drain oils indicate the KA24E procedure does not degrade the lubricant to the extent seen in the Sequence VE test, valve train wear appears to proceed in a similar manner in both tests.

The Cooperative Lubrication Research (CLR) Oil Test Engine, usually called the L-38, has been used for nearly 25 years to evaluate copper-lead journal bearing protection of gasoline rnotoroils under high-temperature, heavy-duty conditions. The test is sensitive to aggressive surface active additives that may encourage bearing corrosion. The L-38 also provides an estimate of oil durability, assessing the resistance of an oil to the accumulation of acidic by-products of combustion that could attack copper-lead bearings. However, the L-38 engine dynamometer test uses a heavily leaded gasoline that is no longer representative of the commercial fuels available in North America, Europe, or Japan. Rather than discard the L-38, this paper describes work to modify the L-38 procedure to run with unleaded gasoline.