Diesel engines is an internal combustion engine with high thermal efficiency, which also uses biodiesel fuel, an environmentally friendly, non-toxic, and low sulfur content. Biodiesel has been around for a long time due to its similar characteristics to diesel fuels which has limited availability. However, several disadvantages are associated with biodiesel, such as poor volatility and high viscosity, which reduces engine performance. Therefore, this study was carried out to improve the diesel engine performance by mixing biodiesel with ecodiesel (ED), an additive produced from natural ingredients that is dissolvable in biodiesel. The biodiesel fuel properties used are density 860 kg/m 3 , dynamic viscosity 4.50E-06 m 2 /s, cetane number 45, and flashpoint 52°C. The results showed that biodiesel-ED mixture could improve engine performance and the optimum performance was at a speed of 3000 rpm on 43.30 (kW), 124.93 (N.m) of the engine torque, and 2.45E -5 (kg/kW.s) of the specific fuel consumption. According to paired sample t-test, the difference in the engine performance is only experienced in the torque, which has a significant increase in the composition of the biodiesel+ED by 0.07 gr mixture.