Due to the demand in the fossil fuels, biodiesel plays very significant role in recent years. The fuels have a disadvantage on oxidation stability and the cold filter plugging point. Some biodiesel have lesser oxidation stability and some can't withstand lower atmospheric temperatures. Many researchers have done the work in the field to improve the cold flow properties of the fuels, such as cold filter plugging point (CFPP), pour point (pp) and oxidation stability. The current research work is a novel method to enhance the quality of exhaust by using mixed biofuel of Candlenut and soapnut. The Soapnut oil is non-edible oil having good oxidation stability compared to many biodiesels, whereas candlenut oils having low oxidation stability but shows higher cold filter plugging point. The engine run was performed by combining 35% candlenut biofuel and 65% soap nut biofuel with the blends of B20 and B40. The Brake thermal efficiency (BTE) of the engine, Specific fuel consumption (SFC) of the engine and the contents of exhaust which majorly include NOx, CO, HC, and smoke density are studied.