A defective thermostat can result in engine overheating and potential internal damage. Improve the reliability of your 6.4L cooling system with the Mishimoto Ford 6.4L Powerstroke Low-Temperature Thermostats! These thermostats are designed as a direct-fit replacement for your aged factory units. The Mishimoto thermostats have a lower activation temperature (187A Degree F/197A Degree F) compared to the factory thermostats (192A Degree F/203A Degree F). The lower activation temperatures allow coolant to flow through the engine earlier, which reduces and maintains lower engine temperatures. These thermostats are ideal for use in warmer climates or under extreme towing/driving conditions. Pair this thermostat set with the Mishimoto 6.4L Powerstroke Aluminum Performance Radiator for a complete cooling system overhaul. As with all our products. ensuring superior product quality and craftsmanship.