This study investigates water-silver nanofluid as a high-performance coolant for automobile radiators to improve heat transfer performance. The radiators are one of the most vital parts of an engine cooling system because the engine performance must be maintained by rejecting heat to the environment. To improve the heat transfer performance, silver nanoparticles (5–8 nm) dispersed in water at a concentration of 4000 ppm was used instead of the conventional coolant fluids. Experiments were carried out at different flow rates (0.04–0.38 L/s) and inlet temperatures to establish the thermal behavior and performance of this nanofluid. The result is an enhancement of 13% in heat transfer coefficient compared to base fluid, and enhancements were found to correlate positively with increases in flow rates and inlet temperatures. This enhancement is attributed to the improved thermal conductivity of the nanofluid and its action in breaking the thermal boundary layer, hence, enabling the increase in convective heat transfer. These results show the tremendous potential for the water-silver nanofluids to be an eco-friendly, energy-saving alternative in automotive cooling systems. The present paper is one addition to a growing number of works dealing with nanofluid applications in thermal management and provides information on their feasibility and benefits. Future work should concentrate on the optimization of nanoparticle concentrations to ensure long-term stability and address economic factors in order to promote the adoption of nanofluids in commercial and industrial systems.