Attention to greenhouse gases is carried out by reducing CO2 emissions. Emission reduction is achieved using mixed fuels, primarily derived from plant oils. The Pertasol-diethyl ether and tamanu oil fuel mixture were tested using a spark ignition engine. The research objective is to obtain fuel specifications and test engine performance using the resulting Fuel. Mixed fuels were created from various compositions with codes ranging from BE0 to BE10. Performance testing was conducted using a 110-cc gasoline engine with specific specifications using mixed fuels and compared to commercial gasoline. The research results indicate that engine torque, power, and MeP are higher when using mixed fuels BE0 - BE10 than retail gasoline. The maximum torque that can be achieved is 8.51NM at 5000 RPM using BE10 mixed fuel, higher than the maximum torque of commercial gasoline, which is 6.81 NM. The highest full power is generated by BE10 fuel, at 7.75 HP at an engine speed of 7000 rpm. The minimum capacity is produced by BE0 fuel, with a power of 6.78 HP at an engine speed of 7000 rpm. Optimal SFC occurs in the BE0 fuel mixture at 7000 rpm engine speed at 0.25 kg/Hp.h. BE10 thermal efficiency reached 31.8%, which is better than commercial gasoline.