Synthetic lubrication oil influences on performance and emission characteristic of coated diesel engine fuelled by biodiesel blends

•Synthetic lubricant provides the maximum performance benefits.•Synthetic lubricant is capable of retaining satisfactory viscosity.•Synthetic lubricant is to increase the life of the engine.•Improvement in efficiency of the coated engine with synthetic lubrication.•No significant changes in the coated engine emission with synthetic lubricants. In this study, the effects of using synthetic lubricating oil on the performance and exhaust emissions in a low heat rejection diesel engine running on Pongamia methyl ester blends and diesel have been investigated experimentally compared to those obtained from a conventional diesel engine with SAE 40 lubrication oil fuelled by diesel. For this purpose, direct injection diesel engine was converted to Yttria-stabilized zirconia (YSZ) coated engine. The results showed 5–9% increase in engine efficiency and 8–17% decrease in specific fuel consumption, as well as significant improvements in exhaust gas emissions (except NOX) for all tested fuels (pure diesel, B10 and B20) used in coated engine with synthetic lubricants compared to that of the uncoated engine with SAE 40 lubricant running on diesel fuel.