Today, there is an effort to obtain energy from every possible source and waste to meet the oil demand. Waste engine oil is one of them. Although waste lubricating oils have an important economic potential, the environmental effect of these oils is much more important than their economic effect. In this study, various waste engine oil-diesel mixture (0:100, 10:90, 20:80, and 30:70) and various fuel pressure conditions (195-255 bar) experiments were performed for various engine loads (3-12 Nm) in a DI diesel power generator. It was aimed to increase the potential of using waste engine oil as fuel by adding 16 mu mol/L Mn additive to the waste engine oil. For the design of the experiment, 1/8 fractional factorial Taguchi method was applied and the relationship between engine load, waste engine oil, fuel injection pressure and Mn additive with experimental factors has been successfully determined with variance analysis. Using regression analysis, regression equations were obtained for exhaust temperature, specific fuel consumption, light absorption coefficient, and nitrogen oxides. Finally, although waste engine oil causes deterioration on engine performance and emissions, it has been determined that the use of waste engine oil as fuel can be improved thanks to the Mn additive.