Hold on. If there was a leak and the coolant level was low, it's not going to circulate through the heater during prolonged periods of idling. You should find that you suddenly get hot air when you start driving. If that's the case, just fix the leak, fill the system, and be sure to watch for signs of overheating. If that happens, there's an air pocket that needs to be burped out. If that air pocket forms under the thermostat, it won't open. Thermostats only open in response to hot liquid, not hot air.
Having the wrong ratio of antifreeze to water won't cause overheating unless there's way too much antifreeze. Antifreeze doesn't hold as many BTUs of heat as compared to water. Water is better at carrying heat to the radiator, but antifreeze is needed for freeze protection and for the water pump lubricant and corrosion inhibitor additives.
Monday, December 18th, 2017 AT 3:46 PM