Mishimoto Chevrolet/GMC 6.6L Duramax High Temperature Thermostats (set of 2)The Mishimoto Chevrolet Duramax high temperature thermostats activate at a higher temperature than the OEM thermostats, making them the perfect solution for Duramax owners who live in colder climates, or have trouble reaching operating temperatures. Activating at a higher temperature means the thermostats will allow the coolant to stay in the engine longer delaying the coolant flowing through the radiator, which allows the engine to warm up sooner.