To lower engine tailpipe emissions, diesel fuel can be oxygenated. This study examines how adding ETBE to Mahua Pyro Oil (MPO25) mixes changes diesel oil's physicochemical properties. ETBE was added in volumetric ratios of 10%, 15%, and 20%, designated as MPO25ET10, MPO25ET15, and MPO25ET20. Adding ETBE affects density, increases the cetane number, and decreases viscosity. Assessment was made on a single-cylinder compression-ignition engine, measuring NOx, HC, and CO emissions, as well as brake-specific fuel consumption and brake thermal efficiency. Results showed that MPO25/diesel blend with 15% ETBE had similar BTE but slightly higher BSFC. Using 20% ETBE significantly reduced smoke opacity by 48% with a 16% increase in NOx emissions.