How do you change the thermostat in 2008 Ford Fusion?

To change the thermostat in a 2008 Ford Fusion, start by ensuring the engine is cool and disconnect the negative battery cable. Drain the coolant by removing the radiator drain plug, then locate the thermostat housing, typically near the engine's upper hose. Remove the bolts securing the thermostat housing, take out the old thermostat, and replace it with a new one, ensuring the gasket is properly seated. Reassemble everything, refill the coolant, and check for leaks.