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Evolving diesel engine design trends are expected to include fuel systems operating at significantly higher pressures and temperatures than in the past. Accordingly, meaningful laboratory tests are needed to help guide this development. Two candidate test methods were evaluated in this exploratory study. Scuffing Load Ball-on Cylinder Lubricity Evaluator (BOCLE) and Modified High-Frequency Reciprocating Rig (HFRR) test results covering a range of operating temperatures were compared with fuel property data. Correlations of the Modified HFRR test data with BOCLE results were also made.

This paper reviews some of the background which demonstrated that there were significant variations in the performance of commercial CD engine oils in highway truck and other heavy duty applications by the mid - 1970's. The paper reports that by 1979 service experience also showed that engine miles to overhaul were significantly improved when SAE 15W-40 oils were used in place of the earlier typical SAE 30 products. By 1983 it had been established that there was a 2 to 1 variation in miles to overhaul between the poor and the best 15W-40 oils. This service background was the stimulus for the development of a proprietary heavy duty diesel engine oil intended to provide customers with a product incorporating the best available engine oil technology. The initial objective was to maximize engine durability.

This paper reviews some of the ways that the Institute of Materials (IOM) North American Engine Oil Database has been used by the authors to relate to issues that they have encountered from time to time. Examples include those of following oil characteristic trends, relating oil properties to industry specifications, evaluating analytical test methods, guiding the writing of engine manufacturers- engine oil recommendations, and helping to resolve service problems. Computer equipment and software requirements to facilitate database access are also discussed.

A high speed road test procedure was developed to demonstrate performance of multigrade engine oils in journal bearing wear protection. High shear viscosities of test oils were approximated through use of a pump loop. A reasonable first approximation of critical viscosity for bearing failure is estimated by measurements at 149°C and about 5Xl05 sec -1 with the pass/fail limit being about 3.5 cSt.

Some of the variables influencing engine and oil performance are reviewed. It is shown that the oil quality, the oil change interval, and the type of service are all important factors affecting engine durability. Careful attention to the selection of quality lubricants and consideration of service factors can reduce vehicle operating costs.

The use of multigrade (V.I. improved) oils in automotive engines has increased significantly in recent years. However, the performance of these oils in terms of factors such as oil economy, wear, and noise, is not always equal to that of single grade oils. Although the initial viscosity of multigrade oils is related to both the base oil and the V.I. improver, the viscosity decreases with use, with the primary factors determining the magnitude of the change being the degree of shear and the characteristics and concentration of the V.I. improver used. This decrease in viscosity has been assumed to be the cause of the decreases in oil economy that may occur with oil use. However, viscosity changes are not believed to be the primary factor responsible since similar oil economy changes have also been observed for single grade oils. Nevertheless, the characteristics and concentration of the V.I. improver used can be a significant factor influencing oil economy.

Engine oil test Sequences IIA and IIIA have been developed to replace Sequences I, II, and III. These new sequences are designed to evaluate lubricants for use in current passenger car engines under severe (MS) service conditions. Lubricant performance is evaluated with respect to scuffing wear, rust, corrosion, deposits, and rumble. The Sequence IIA and IIIA test procedure involves major changes which affect the evaluation of engine rusting and provides improved correlation between test results and short-trip service. Average engine rust ratings correlate with service data within ±0.5 numbers. The new test also provides better repeatability and reproducibility in a significantly shorter schedule. The rust repeatability and reproducibility is less than ±0.2 and ±0.6 numbers, respectively. Test time has been reduced 52%.

ANALYSES of crankcase vent gases by several methods have shown that crankcase and exhaust hydrocarbon emissions from automobiles are of the same order of magnitude. Internal ventilation of the crankcase to the engine intake system eliminates crankcase emission, thus providing a practical control of this important source of air pollution.*

This paper presents the results of an interference microscope study of the action of oil additives on metal surfaces in sliding contact and indicates that valuable information can be obtained from a study of the worn surface. It is shown that the operation of engine cams and valve lifters on oils containing zinc dithiophosphate additives can result in an increase in the small-scale roughness of the lifter-foot surface over that obtained by operation of the same parts on oils which do not contain the additive. In addition, the development of this surface roughness is also influenced by operating time, stability and concentration of the additive, and composition of the contacting surfaces. Although the mechanism involved is far from being completely understood, the increase in small-scale roughness is believed to result from a reaction of additive decomposition products and the surface.