To reduce the economic impact caused by the fossil fuel crisis and avoid relying on existing biofuels, it is important to seek locally available and renewable biofuel throughout the year. In the present work, a new light biofuel—Melaleuca Cajuputi oil (MCO)—was introduced to blend with refined palm oil (RPO). The physicochemical properties, combustion characteristics, engine performance, and exhaust emissions were comprehensively examined. It was found that the higher the percentage of MCO, the

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... lower the viscosity and density of the blends obtained. Calorific value (CV) was increased with the increase of MCO fraction in the blend. Regression analysis has suggested that the blend of 32% (v/v) of RPO and 68% (v/v) of MCO (RPO32MCO68) is optimal to obtain viscosity and density in accordance with ASTM 6751/EN 14214 standards. The experimental results show that the in-cylinder pressure, brake torque, and brake power of the optimal blend were slightly lower than those of baseline diesel fuel. Brake specific fuel consumption (BSFC), carbon monoxide (CO), and unburnt hydrocarbon (HC) were found to be slightly higher compared to diesel fuel. Notably, nitrogen oxides (NOx) and smoke opacity were found to be decreased over the entire range of the test. Overall, the optimal blend of RPO32MCO68 has shown a decent result which marks it as a potential viable source of biofuel.