2000 Grand AM water vs coolant
Ok guys I'm sorry but this could be a long post as I feel you need to know everything I've done to maybe give an informed answer.
I have the above car. When I bought it, It would over heat on me all the time. I replaced the water pump thermostat and hoses, still overheating. So I did research on it and it turns out that I needed to burp the cooling system. Now I didn't have the money to put coolant in so I ran water and everything was great it ran (depending on how I drove it) from 180 deg to 195 deg. Next payday I bought 2 gallons of 50/50 antifreeze (green) and it ran at 210 deg to 230 deg (again depending on how I drove it). Thinking I ran the wrong coolant I bought 2 gallons of 50/50 extended life (orange) and it ran the same as the green.
I took the car to GM to have the ignition recall fixed (only made a key for me) and asked the tech why the car ran cooler on water than coolant. He explained the difference between running water and coolant but that didn't answer my question.
He said if you run water it will rust the engine unless you run distilled water. Then he told me running straight coolant the car would never reach operating temperature. Thinking like that I drained 1 gallon from the system and replaced it with straight concentrate antifreeze.
So here is my question, if it has mostly antifreeze (which is suppose to make run way below 195 never reaching operating temperature) why does it run at a constant 230 no matter how I drive it, and can someone explain why it runs cooler on water.
I appreciate your feedback
Thanks