Estimation of Oil Drain Life of Engine Oils in New Generation Diesel Engines in Tropical Conditions 2011-01-2405

Field trials are carried out on diesel engines operating in tropical conditions at higher dust levels, temperature, humidity and load factor than the European and North American conditions. Passenger buses and trucks with engines of sump capacity 0.061-0.110 litre/hp and SAE15W40 viscosity oil meeting API CG-4+, API CH-4, API CI-4 from Group-I and Group-II base stocks are considered. Results show that the CH-4 oil is best suited for the subject engines. Oil drain interval is found proportional to the sump volume for the same stress on oil. Group-II base oil performed better than Group-I in limiting TAN and controlling oil consumption. Cost effective oil with a TBN of eight is sufficient with low-sulphur fuels without affecting oil drain interval. Iron concentration and kinematic viscosity decide useful oil life with respect to the limits fixed by the engine manufacturer. Oil life is found to be higher for passenger buses than trucks. The engine wear is more a function of silica concentration, load factor and age than the API category of oil.