How do you change a Buick rendevous thermostat 2003?

To change the thermostat on a 2003 Buick Rendezvous, first, ensure the engine is cool and disconnect the negative battery cable. Locate the thermostat housing, typically at the engine's front, and remove the bolts holding it in place. Take out the old thermostat and clean the mating surfaces before installing the new thermostat, ensuring it sits correctly. Finally, reattach the housing, reconnect the battery, and refill the coolant as necessary.