The use of plant-based fuels has resulted in addressing social problems since growing of these plants will consume more cultivated land and freshwater resulting in an imbalance of the food chain due to constant increase in the world population. Hence to address these problems, this work is mainly focused on the alternative fuels derived from neem seeds which are non-edible and have high viscosity, by the two-step transesterification process the viscosity gets reduced and the properties are comparing with the diesel fuel, so that neem biodiesel used as the fuel. By the literature review, the study focused on oxygenated additives which have high oxygen content, which improves the combustion and emission characteristics. Also from the waste oil biodiesel can play an important role to reduce the global energy demand due to its availability, renewable properties, and environment-friendly.