Effect of Diesel Engine Oil Formulation on Optimum Lube Performance in IDI Engines of Multi-Utility Vehicles

In an earlier paper^[1] we had emphasized the need for diesel engine lubricants meeting specific built-in specifications to combat the stress emanating out of the geographical, operational and engine design requirements in Indian subcontinent for heavy duty sectors. In this paper we present our work in identical domains for a segment utilizing passenger car and/or utility vehicles. This paper presents our work on development of a diesel engine oil to meet the specific requirements of a thermally-stressed IDI engine with respect to key performance attributes. The laboratory optimization for thermo-oxidative stability typical of requirements for IDI engines coupled with higher level of dispersancy and wear inhibition that are identified with current generation lube oils have further been established in engine test programs. The superior performance has been established in endurance test on a representative engine. This was followed by validation in field run on 2 vehicles using such IDI engines generating 95 bhp. The final validation of the performance attributes was made in back-to-back evaluation cycle with reference and candidate diesel engine oils in 4 phases on a single vehicle running on the representative IDI engine offering 72.5 bhp. The test matrix included defined variable of optimization with respect to both the performance additive systems and base oils. Cumulative effect of additive synergism and base oil properties have been found to result in the long drain potential being established.