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Majority of light and heavy duty commercial vehicles on road in India use API-CF grade lubricants. Soot accumulation in lubricating oil can result in engine wear and lubricant’s viscosity increase thereby affecting its pumping ability and drain interval. Due to faster lubricant degradation and with emergence of newer engine technologies, there is increasing demand of improving performance of lubricants particularly with respect to soot dispersancy. This paper describes the various engine hardware modifications and optimizations carried out on a commercial BS II, 4-cylinder turbocharged diesel engine in order to develop a flexible engine test procedure for evaluating the lubricant’s dispersancy/anti wear characteristics up to 6% soot levels.

In the light of major research work carried out on the detrimental health impacts of ultrafine particles (<50 nm), Euro VI emission standards incorporate a limit on particle number, of which ultrafine particles is the dominant contributor. As Compressed Natural Gas (CNG) is a cheaper and cleaner fuel when compared to diesel, there has been a steady increase in the number of CNG vehicles on road especially in the heavy duty segment. Off late, there has been much focus on the nature of particle emissions emanating from CNG engines as these particles mainly fall under the ultrafine particle size range. The combustion of lubricant is considered to be the dominant source of particle emissions from CNG engines. Particle emission due to lubricant is affected by the oil transport mechanisms into the combustion chamber which in turn vary with engine operating conditions as well as with the physico chemical properties of the lubricant.

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.