High viscosity of vegetable oil causes ignition problems when used in compression ignition engines. There is a need to reduce the viscosity before using it as engine fuel. Preheating and pre-treating of vegetable oils using waste heat of exhaust gases is one of the techniques, which reduces the viscosity and makes it possible to use it as alternate fuel for some niche applications, without requiring major modifications in the engine hardware. Several applications such as decentralized power generation, agricultural engines, and water pumping engines, can use vegetable oils as an alternative fuel. In present investigation, performance, combustion, and emission characteristics of an engine using preheated 20% blend of Jatropha oil with mineral diesel (J20) has been evaluated at a constant speed (1500 rpm) in a single cylinder four stroke direct injection diesel engine. Analysis of cylinder pressure, rate of pressure rise, heat release rate and cumulative heat release was done in addition to engine performance parameters such as brake thermal efficiency, brake specific fuel consumption and brake specific energy consumption. Regulated emissions such as CO, CO2, THC, NO and smoke were also measured in this comparative study. Since noise regulations are becoming stringent, therefore noise levels were measured (dBA) and combustion noise was calculated from cylinder pressure data from combustion analysis of the engine. Vibrations were measured using accelerometers at vertical, lateral and longitudinal directions. Noise and vibration analysis of the engine has also been carried out to assess vegetable oil's performance on these parameters vis-a-vis baseline mineral diesel.