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Improvement in fuel economy and reduction in emissions are the two major driving forces in the advancement of automotive engine technologies, fuel quality, lubricants, and aftertreatment devices. Engine design, operating conditions such as speed and load, and engine oil behavior have a significant influence on engine friction and then the vehicle fuel economy. There is no standard short duration engine test available to evaluate engine oil’s friction. This study developed a test protocol to discriminate friction reduction efficacy of engine oils/additives to support in the development of engine oils. The engine test facility was modified to conduct the motoring test over the speed range of 1000 - 4500 rpm and at 50 - 100 °C coolant and oil temperatures. Different viscosity grades and additive chemistry i.e. combination of friction modifiers & viscosity modifiers was evaluated over the motored torque test.

In this paper, the characteristics of particle size distribution in the exhaust of a turbocharged 5.9 liter Cummins gas engine lubricated by two commonly used oils of different viscometrics (15W-40 and 20W-50) have been investigated. The study also attempts to differentiate the performance of the lubricants on the basis of fuel economy. A test procedure developed in- house was used for the evaluation, wherein the engine was operated at various speeds (1200-2800rpm) and load (25 %, 50% & 75%) conditions. Particle size distribution is measured using Engine Exhaust Particle Sizing Spectrometer (TSI EEPS Model 3090). Results indicate that a majority of the particle emissions are observed in the nucleation region (particle diameter < 50nm) and particle size distribution is found to significantly vary with engine speed.