I'm stumped, my car over cools big time and its is only -1C out. Here what happens, I'll start driving and my car heats up to normal operating temp, stop driving and in like a minute it goes from hot to cold. I tried replacing the thermostat with a new one from a dealership and the coolant however no luck. Is there anything else I could change or check? Thanks

 

..so y is this bad?

 

well, if it gets any colder out and I want heat in my car, I dont have any because the engine is cold