How do you change 09 Malibu thermostat?

To change the thermostat on a 2009 Chevy Malibu, first ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the radiator and remove the thermostat housing by loosening the bolts. Replace the old thermostat with the new one, ensuring the gasket is in place, then reattach the housing and refill the coolant. Finally, reconnect the battery and start the engine to check for leaks.