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Many vehicle and engine test studies have shown that the fuel efficiency of automobiles can be improved by reducing friction between moving parts. Typically, organic friction modifiers such as glycerol monooleate (GMO) or metal containing friction modifiers such as molybdenum dithiocarbamate (MoDTC) have been added to engine oils to reduce boundary friction and improve fuel efficiency. These traditional friction modifiers act by forming either a self-assembled organic film (in the case of GMO) or a Mo-disulfide chemical film (in the case of MoDTC). More recently, the ability of inorganic tungsten disulfide (WS2) nanoparticles to reduce boundary friction has been described. Martin has proposed that WS2 nanoparticles are transported into a contact zone where they are compressed and peel open like an onion to form a film. In this study, oil-soluble inorganic nanoparticles containing cerium (Ce) and zinc (Zn) have been synthesized.

Modern light-duty trucks and SUV's are designed to be aerodynamic to increase fuel economy. Such vehicle design significantly reduces the amount of air available to cool the rear axle in rear wheel drive vehicles. Reduced cooling coupled with higher power output and additional load from trailer towing operations results in higher axle operating temperatures, especially during the early operation or “break-in” phase of axle life. Higher axle operating temperatures decrease oil viscosity resulting in reduced oil film formation ability to protect against wear and contact fatigue. High temperature also shortens the useful life of gear oils. To facilitate the development of gear oils capable of reducing axle operation temperature, we have developed a laboratory simulation test method that can closely simulate actual trailer-towing driving on Baker's grade road under maximum GVCWR of close to 6,033 kg (13,300 lbs).

Biodiesel fuel is a promising new renewable, alternate fuel source. However, its effect on diesel engine oil lubrication is largely untested at present. There is some indication that the use of biodiesel fuel can degrade diesel engine oil performance to such an extent that shortening of oil drain intervals is required. Oil which is fuel-diluted with biodiesel, which is known to contain unsaturated hydrocarbon bonds, would be expected to be more prone to oxidation. Current diesel engines designed to meet environmental standards tend to introduce more soot into the crankcase oil. The new diesel engine oils for use with biodiesel fuel must be capable of dispersing soot to minimize soot-induced viscosity increase of the oil and prevent engine wear. Oils will also need improved oxidation and corrosion inhibition. To examine soot-handling, ASTM D 7156 Mack T-11 engine test results with 20 wt% soy methyl ester in ultra-low sulfur diesel fuel (B20) were employed.

In the latest passenger car motor oil specifications the Sequence IIIG engine test is used to determine the ability of lubricants to control piston deposits. We have analyzed the chemical composition of Sequence IIIG deposits in order to determine the source of the piston deposits and determine if the mechanism for deposit formation in the Sequence IIIG engine test is similar to previously published mechanisms for formation of high temperature engine deposits. These previous mechanisms show that combustion by-products react with lubricant in the piston ring zone. The mixture of combustion by-products and lubricant are oxidized to form deposit precursors which are further oxidized to form deposits. Since the Sequence IIIG engine test uses lead-free fuel it is important to reexamine the nature of piston deposits formed in gasoline engines and in particular in the Sequence IIIG engine test.