You have a hole in the cooling system, possibly a pin hole in a radiator hose.
Coolant Temperature Sensor
If your looking at the engine its on the right hand side of the throttle body, below the black plastic intake manifold.
blown head gasket
bad sensor
more likely to be a faulty coolant sensor or the thermostat is faulty and staying open
On a 2003 Pontiac Grand Am, the coolant bleeder valve is located on the engine near the thermostat housing. It typically appears as a small screw or bolt. To bleed the cooling system, you would loosen this valve while the engine is running, allowing trapped air to escape until a steady stream of coolant flows out. Ensure the engine is at operating temperature for effective bleeding.
Could be,Low on coolant,A stuck closed faulty thermostat,A faulty cooling fan motor/system,
You may have a blown head gasket. Have it pressure tested. The head gasket keeps the cylinder head sealed from the water that circulates through the heads to keep them cool. If the gasket gets a hole in it, then there is a gap in which oil can get into your coolant. Make sure what you are seeing is OIL in the coolant first.
A bad head gasket , a warped head usually from overheating , would allow engine coolant into an engine cylinder
The normal direction of circulation in the coolant system would push the coolant out the thermostat opening.
coolant levels or the thermostat
Yes, it controls the coolant flow around the engine block, without coolant the engine would overheat.