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Automobile OEMs are looking for improving fuel economy[1,2] of their vehicles by reducing weight, rolling resistance and improving engine and transmission efficiency apart from the aerodynamic design. Fuel economy may be improved by using appropriate low viscosity [3] and use of friction reducers (FRs)[4,5] in the engine oils. The concept of high viscosity index [6] is being used for achieving right viscosity at required operating temperatures. In this paper performance properties of High Viscosity Index engine oils have been compared with conventional VI engine oils. Efforts have been made to check the key differentiation in oil properties w.r.t. low temperature fluidity, high temperature high shear viscosity/deposits, friction behavior, oxidation performance in bench tribological /engine/chassis dyno tests which finally lead to oil performance assessment. Three candidates of SAE 0W-30 grade oil with ACEA C2/API SN credentials have been chosen using various viscosity modifiers.

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.