In recent times conventional heat transfer fluids such as water and engine oil are widely used in the automobile radiator. However, to improve the thermal performance of the system, a lot more is required from the aspect of the heat transfer fluid. Major improvements in cooling capabilities have been constrained because of poor thermal conductivities of the working fluids, which is vital in the enhancement of heat transfer. The use of nano-sized (1-100, nm) solid particles as an additive suspended in the base fluid is one of the technique to enhancement heat transfer. This study aims to evaluate the performance of the heat transfer characteristics of water/anti-freezing based nanofluid as a coolant for car radiator. For the based fluid, a mixture of water and Ethylene Glycol were used with concentration of 50% for each of the fluid. Al2O3 and. CuO nano particles of concentration 0.05%, 0.15% and 0.3% were added to the base fluid and then evaluate the heat transfer characteristics of the nanofluid. The mass flow rate of nanofluid in the flat tube was kept constant. The heat transfer models are simulated using ANSYS fluent solver. The performance of the heat transfer characteristics were evaluated based on certain parameters which are the heat transfer coefficient, thermal conductivity, Nusselt number, and rate of heat transfer of the nanofluids. It was found that the nanofluid that exhibited the highest heat transfer performance was the CuO nanofluid. The heat transfer coefficient was recorded at 36384.41 W/m(2) K, the thermal conductivity was 1.241 W/m K, Nusselt number was 208.71 and the rate of heat transfer was at 28.45 W. The Al2O3 nanofluid had a heat transfer coefficient of 31005.9 W/m(2) K, thermal conductivity of 1.287 W/m K, Nusselt number was 173.19 and the rate of heat transfer was at 28.25 W. (C) 2017 Elsevier Ltd. All rights reserved.