Now a day's, nanoparticles are extensively used to increase the thermal conductivity, heat transfer rate and tribological properties of the engine lubricant by adding nano additives to form nanofluids. Accumulation of nanoparticles in engine lubricant may reduce friction with the improvement of the lubrication characteristics. In order to reduce the friction and wear lubricants are used, but still, the fuel consumed for frictional losses is about ten to twenty percentages of the total fuel supply. This research work focuses on the preparation of nanolubricants by selecting suitable commercial engine oil, biodegradable oil and nanoparticles based on tribological performance for multicylinder petrol engine applications. The copper oxide nanoparticles and SAE15W40 commercial engine oil and punga oil as biodegradable oil used. The nanolubricants were prepared by adding nanoparticles to the base oils with 0.1% concentrations. From the results it was found that, SAE 15W40 with 0.1% copper oxide is the best nanolubricants for the applications multi cylinder petrol engine.