Green fuels also called green hydrocarbons, biofuels, are fuel produced from biomass sources through a spread of biological and thermochemical processes. These products are almost like petroleum gasoline and diesel fuels and are therefore considered fully infrastructure compatible fuels. They will be utilized in engines without engine modification. This paper presents a comprehensive review on the potential of biodiesel from different waste feedstock biodiesel like waste vegetable oil and waste plastic oil. Furthermore, the effect on the engine performance, combustion and exhaust emissions including details of engine and operating condition also review during this paper. The most goal of this paper is to supply information to the engineers, industrialists and researchers who have an interest on waste biodiesel and to prominence waste biodiesel as a promising alternative replacement for fossil fuels. An outsized number of literatures from highly rated journals in scientific indexes are reviewed including the foremost recent publications.