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A test program has been conducted to evaluate the low-temperature cranking, pumping and starting characteristics of light and heavy duty diesel trucks using various lubricants. The low-temperature performance of oils with different SAE viscosity grades and base stock type were evaluated. Included are formulations based on conventional mineral, hydrocracked and synthetic base stocks. The results show that lower viscosity grade oils using special base stocks, in particular synthetics, demonstrate improved low-temperature cranking and pumping performance over conventional lubricants. The engine test results are compared against laboratory low-temperature flow, cranking and pumpability tests.

The development of extreme pressure and limited slip automotive gear oils requires care in the selection of base stocks and additives in order to achieve the desired balance of performance properties. Considerations involved in selection of extreme pressure agents, corrosion inhibitors, and friction modifiers are enumerated. Of particular interest is the interference of many corrosion inhibitors and friction modifiers with the desirable gear protection properties. Tests are described for use in evaluating the additives, and performance properties of fully formulated oils are shown. The need for a special lubricant for limited slip axles is described.

Turbocharging of gasoline-powered passenger car engines, to provide improved performance while maintaining good overall fuel economy, has been adopted by some U.S. and overseas builders. The high temperatures encountered in turbochargers can seriously affect the engine oil life. Under certain severe operating conditions excessive oil degradation deposits can be formed in the turbochargers which can lead to bearing failure. A vehicle chassis-rolls test procedure was developed to evaluate lubricant composition effects on turbocharger deposits and bearing condition. Evaluations of a number of different engine oils have demonstrated superior performance for one class of synthetic oil over high-quality mineral oils in lubricating the high-temperature areas of passenger car turbochargers.

Blends of up to 20% methanol in gasoline were evaluated in both engine dynamometer and controlled vehicle tests, and in a 50,000 mile road test. Performance comparisons between methanol blends and base gasolines were made in vehicle driveability and vapor lock tendency, engine deposits and wear, fuel economy, exhaust emissions, compatibility with fuel system materials, and phase stability of the blends. Vapor lock tests in six 1974 cars strongly suggested that the vapor lock tendency of methanol blends is greater than would be predicted for gasolines having the same volatility characteristics. Cold start and warm-up driveability of two 1974 cars at 70°F depreciated as methanol concentration increased in base fuels of three volatility levels. These driveability data were found to correlate well, at a given methanol concentration, with fuel volatility characteristics described by means of a new fuel vaporization pressure technique.

Studies have been conducted which illustrate the excellent overall performance of a synthesized passenger car engine oil during greatly extended drain intervals. These studies were conducted primarily with automobiles manufactured in the U.S. and with typical U.S. service. Supporting data are presented in areas of engine cleanliness, engine wear, and lubricant stability from several types of service conditions including heavy duty taxicab and police car operations as well as typical everyday consumer driving. Information is also provided from a high mileage test using the EPA durability cycle. These field test results correlate well with extended duration API SE sequence data.

Two synthesized commercial engine oils have been developed and extensively evaluated to document a number of unique performance benefits. The benefits include significant fuel savings in heavy-duty diesel truck engines, excellent low temperature fluidity, engine cleanliness and antiwear protection, extended drain capability, and good oil economy. The results of standard and double-length laboratory engine tests, chassis rolls tests and confirming field tests are discussed in the paper.

A new class of synthetic fluids has been developed with specific physical and chemical properties, which can be used to formulate automotive engine lubricants with a performance range far exceeding that obtainable with conventional mineral-oil-based lubricants. New, unique synthetic engine lubricants are described that provide improved low-temperature fluidity and cold-starting performance, better high-temperature stability and engine cleanliness, outstanding viscosity stability, reduced oil consumption, better oil pressure retention, and reduction of engine wear. The superiority of these new synthetic lubricants is documented with results of evaluations conducted in a wide range of engines and vehicles using standard and newly developed test procedures. Testing under severe rally and field conditions is also discussed.

A light viscosity engine oil formulation has been developed based on an extension of the synthesized hydrocarbon fluid (SHF) lubricant technology presented in a recent SAE paper by B. J. Miller, et. al. Utilization of these base materials has enabled the formulation of a product, designated XRN 1669, which provides a significant improvement in both fuel economy and oil consumption control. A combined improvement in these two performance areas has not been attainable in the past with conventional mineral oils. In addition to fuel and oil economy, other critical areas of performance are investigated, including engine cleanliness, wear protection and cold starting capability, as well as ONRI and exhaust emission effects. The superior performance of XRN 1669 compared to premium quality multiviscosity mineral oil products is documented in extensive laboratory, engine and field tests.

Unique performance advantages for polyalphaolefin (PAO) based synthetic engine oils have been documented since the mid-70's (1). The superior performance of these lubricants led the industry to develop improved mineral-based lubricants, including those produced by isomerization of waxes. Recently, an extensive research project was initiated to further enhance the performance advantages of PAO-based synthetic engine oils compared to highly refined mineral oils. A new generation of synthetic lubricant was developed delivering significantly improved performance in all areas. Although the development took place before the introduction of the API “SH” engine oil category, this new synthetic engine oil technology far exceeds API “SH” requirements as well as the API “CD” diesel performance specification. This paper discusses the standard and extended-length (U.