How do you replace a thermostat in an 1991 Oldsmobile delta 88?

To replace the thermostat in a 1991 Oldsmobile Delta 88, first ensure the engine is cool, then disconnect the negative battery cable. Drain the coolant from the radiator, and remove the upper radiator hose connected to the thermostat housing. Unscrew the thermostat housing bolts, remove the old thermostat, and install the new one with the spring side facing the engine. Reassemble everything, refill the coolant, and reconnect the battery cable.