The present work includes the production of six blends of biodiesel using waste cooking oil/mustard oil with methanol (99% pure) having NaOH/KOH (91% pure) as the catalysts. The kinematic viscosity, density, calorific value, flash point, cloud point, pour point, and cetane number of prepared bio-fuels were determined. The comparative energy-exergy analyses for six biodiesel fuels were conducted using a 4 inline-4stroke diesel engine with 2392 cc at 0%, 25%, 50%, and 100% load for constant/varying speed. The break-power (BP), heat taken by cooling water (Q(w)), heat taken away by exhaust gases (Q(ex)), and unaccountable losses were evaluated. It was found that the tested biodiesels offer competitive energetic performance to the diesel. The exergetic performance parameters followed similar trends with the corresponding energetic ones, but with increased brake specific fuel consumption and reduced exhaust emission due to higher oxygen content in biodiesel fuel. The results of analysis of variance clearly reflect that the B.P. is influenced most by the load, followed by the type of oil and speed has the least effect. It was also found that the biodiesels are having considerably lower CO emission than diesel. NOx emissions were least at higher load in diesel followed by waste cooking oils. Soot emissions were alike for diesel, waste cooking oils, and mustered oils at low load, but at higher load diesel has an exponential increment in soot emissions.