How do you change the thermostat in your 1994 Cadillac Seville sls?

To change the thermostat in a 1994 Cadillac Seville SLS, first, ensure the engine is cool and disconnect the negative battery terminal. Remove the upper radiator hose from the thermostat housing, then unbolt the housing to access the thermostat. Replace the old thermostat with a new one, ensuring the gasket is in place, and reassemble by tightening the housing and reattaching the hose. Finally, reconnect the battery and refill the cooling system if necessary.