The increasing demand of nanofluids in cooling applications has led to increased attention from many researchers. This increased thermo physical properties of nano particle can be applied for better performance in energy, heat transfer and other performance. In this paper a survey of heat transfer enhancement through oxide form of nanoparticle and metal form of nanoparticle is done and the results are interesting that nanofluids enhances the heat transfer rate in all heat exchangers. Radiators are compact heat exchangers optimized and evaluated by considering different working conditions. The cooling system of a car plays an important role in vehicle's performance, consists of two main parts, known as radiator and fan. Improving thermal efficiency of engine leads to increase the engine's performance, decline the fuel consumption and decrease the pollution emissions. Effects of fluid inlet temperature, the flow rate and nano particle volume fraction on heat transfer are considered. Results show that there is increased thermal conductivity with increases in volume fraction of nanoparticle. The results also says that there is increased heat transfer rate in metal form of nanoparticle compared with the oxide form is noted. Comparing with conventional fluids the nanofluids either metal or oxide form has enhanced heat transfer rate. Through this survey the importance of nano sized in heat transfer is understood and the reason behind the enhanced heat transfer the mechanism given by various researchers is also compiled even though there is no clear definition towards the nano particle heat transfer. The results of heat transfer in radiator by various nanofluid also suggest that there is improved heat transfer rate. The enhanced heat transfer principle of nano sized particle also favours for the miniaturization of the heat exchangers especially like radiators.