Extreme pollution has forced industries to seek environmentally sustainable lubricating materials for the automotive sector. Thus, this study is motivated to explore the possibility of vegetable oils for bio-based lubricant application. This study is established on rubber seed oil that was further chemically modified to decrease the presence of unsaturated fatty acids at the molecular level and make it more convenient for tribological application. In addition, additives have been introduced to the modified oil in varying ratios. During the first phase, phosphonium-based ionic liquid (PIL) and copper oxide (CuO) nanopowder were mixed with the modified rubber seed oil (MRSO) for improved physicochemical properties compared with synthetic ester. They are tribologically tested for their suitability as lubricants in the second phase. The results showed improved physicochemical characteristics, especially MRSO + 1.4% PIL + 0.4% CuO, which further helped reduce friction concerning other samples. Concurrently, combining PIL and CuO nanoparticles as additives also improved thermal stability and decrement in surface wear. MRSO + 1.2% PIL + 0.4% CuO exhibited outstanding anti-friction and anti-wear characteristics. [GRAPHICS] .