> I took the car to a mechanic, who told me that it was impossible to tell whether the thermostat is broken without replacing the radiator first, even though Fl

> I took the car to a mechanic, who told me that it was impossible to tell whether the thermostat is broken without replacing the radiator first, even though FlightCar had wanted to fix both This makes no sense. Replacing the thermostat in most cars is a matter of a $10 part and 15 minutes. You need a pair of pliers and a ratchet. Meanwhile, the only reasons a radiator would warrant replacement would be extreme buildup (indicative of much bigger issues, like a blown head gasket) or a puncture.