In the present work, the effect of various nanofluids on automotive engine cooling was experimentally studied. Al2O3, TiC, SiC, MWNT (multi-walled nanotube), and SiO2 nanoparticles with average diameter ranging between 1 and 100 nm were mixed with distilled water to form nanofluids. An ultrasonic generator was used to generate uniform particle dispersion in the fluid. A compatibility test was carried out on all nanofluids and it was found that TiC, MWNT, and Si3N4 nanoparticles settled and separated from the fluid within 3 hours after preparation. The engine cooling performance testing setup consisted of an Aprilia SXV 450 engine, the nanofluid cooling loop, a radiator, a fan, etc. Thermocouples and resistance temperature detectors (RTD’s) were attached to the inlet and outlet of the radiator hose to monitor the temperature changes taking place in the cooling system. A flowmeter was attached to the inlet hose of the radiator to monitor the coolant flow rate. Results of heat transfer capability were compared for cooling system with and without nanoparticle seeding. It was observed that the heat dissipation capacity of nanofluids increased with increasing volume concentration of nanoparticles and also with increasing coolant flow rate. The results showed that the heat dissipated by TiO2, SiO2 and Al2O3 nanofluids were 31.9%, 27.7% and 12.5% higher than the base fluid, at 3.5 GPM flow rate and at 1% volume concentration of nanoparticles.