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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).

This paper reviews ASTM's work in developing the new API CH-4 diesel engine oil category for 1998. It focuses in particular on three new engine tests - Cummins M-11, Mack T-9, and Caterpillar 1P - which are juxtaposed on existing engine and bench tests in the API CG-4/CF-4 categories. These new tests ensure increased engine durability, while operating at high temperatures and high levels of soot in the crankcase. The high soot levelsMP expected in 1998 emission-controlled engines are a result of retarded fuel injection timing used to lower NOx, combined with high top-ring piston locations used to minimize particulate. API CH-4 is the most robust API diesel engine oil category ever developed. It improves the quality of diesel engine oils for both existing and new engines, using both low and normal fuel sulfur levels. In addition, it will allow a more flexible approach to oil drain intervals, in accordance with the recommendations of the individual engine manufacturers.

A cooperative cold-start and warmup driveability program was conducted by the Coordinating Research Council (CRC) in Yakima, Washington, during the fall of 1989. The program investigated the independent effects of front-end and mid-range volatility on cold-start and warmup driveability of twenty-four late model vehicles at intermediate ambient temperatures (30°F - 56°F). Volatility ranges investigated were those that may be required of future summertime fuels. Mid-range volatility (T50) was found to have a substantially significant impact on driveability, regardless of fuel-system type, while front-end volatility (RVP) was found to show a lesser but still significant effect on carbureted and throttle-body-injected vehicles. Oxygenate content/type was also a significant variable.

A study was conducted under the auspices of the Coordinating Research Council, Inc. (CRC) to assess the potential effects of gasoline octane quality on vehicle acceleration performance. Twelve participating laboratories, representing both the oil and the automotive industries, tested a total of 182 vehicles as part of the 1989 CRC Octane Number Requirement Survey. The vehicles consisted of 78 with electronic knock control systems (knock sensors) and 104 without. All testing was performed using the 1989/1990 CRC FBRU fuel series. The results showed that acceleration performance of vehicles with knock sensors was significantly affected by gasoline octane quality.

The authors measured camshaft surface temperatures in two different gasoline engines: a Ford 2.3-liter overhead-camshaft engine with finger-follower and an Oldsmobile V-8 5.7-liter engine with rotating tappets and pushrods. Using unique surface thermocouples in the cam-lobes, we found that maximum cam-lobe temperatures occur at the cam-nose and increase linearly with speed and oil temperature. At high speed, the rotating tappet produced lower temperatures than the finger-follower. In addition, at maximum speed the cam-lobe temperatures in the ASTM Sequence V-D and IIID tests were similar--200°C. The similarity in these surface temperatures explains why both engines require similar zinc dithiophosphates (ZnDTP) for wear control. The surface temperature controls the surface chemistry.

A pilot study was conducted under the auspices of the Coordinating Research Council, Inc. (CRC) to assess the potential effects of gasoline octane quality on acceleration performance, fuel economy and driveability in vehicles equipped with electronic spark control systems (knock sensors). Fourteen vehicles were tested by five participating laboratories, representing both the oil and automotive industry, on CRC unleaded reference fuels of varying octane quality (78 to 104 RON). The test vehicles included nine naturally-aspirated and five turbocharged models. The results showed that acceleration performance was the parameter most sensitive to octane quality changes, particularly in the turbocharged models. No significant improvements in fuel economy were found with increasing octane. Drive-ability was not affected by fuel octane within the commercial fuel range, but three vehicles showed degraded driveability with sub-commercial octane fuels.

Cooperative test programs were conducted during 1984 and 1985 by the Coordinating Research Council (CRC) to investigate the driveability of hydrocarbon-only and hydrocarbon-alcohol blends. The 1984 program was the first CRC intermediate temperature program on fuels containing alcohols. The 1985 program evaluated the performance of hydrocarbon and hydrocarbon-alcohol blends at higher temperatures. Both programs contained three vehicle subsets that were classified by fuel delivery system-carbureted, port fuel-injected, and throttle body fuel-injected vehicles. Both fuel-injected vehicle sets gave significantly lower demerits compared to carbureted vehicle sets. Fuel volatility and alcohol type/content were found to be significant variables for many of the fuel combinations evaluated.

The low-temperature pumpability performance of multigrade engine oils was evaluated in several United States and European engines. Test oils included both experimental formulations and commercial service station oils; test temperatures ranged between -20 and 0 F. The time for oil to reach engine rocker arms after startup at -15 F and -20 F was not related to low-temperature lubricant properties such as pour point and Brookfield viscosity. Pumpability (that is, oil gallery pressurization rate) of the oils improved markedly in successive cold-temperature starts, probably because of fuel dilution and shearing of microstructures in the oil. Engine design features can significantly affect pumpability performance.