This research work is focused on the regeneration of used lubricating oils which are simply thrown out to the environment. It is evident from the past research outcome that there is an acute shortage of petroleum oils and regeneration of fuels from used lubricating oils can be potential substitute of fossil fuels. But due to some drawback such as higher viscosity and density it cannot be used as a single fuel. In this regard the distillation of used lubricating oil has been carried out with. Further, this distilled used lubricating oil (DULO) was blended in different proportions with Jatropha biodiesel (JB) which has excess oxygen by about 10%. The aim of the current study is to investigate the performance and emission characteristics of a DI diesel engine run on these blends and comparison with base fuel diesel. The behavior of the engine was evaluated in terms of brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature, carbon monoxide emission, hydrocarbon, nitric oxide emission and smoke opacity. The test result revealed that, the behaviour of the engine run on the JBDULO20 (i.e. 80% JB and 20% DULO) blend was better than other blends considered in the study. © 2020 Published under licence by IOP Publishing Ltd.