First of all you need to start ignoring advice from the person you got it from previously. The heater core can not cause overheating except if it has a leak that you ignore. Thermostats give very little trouble. Chemicals are not a fix for a mechanical problem, at least I wouldn't put anything in an engine I'm trusting to get me back home without walking. Reserve tanks aren't even needed for the cooling system to function. They were first put on some car models in the mid '60s. (Some designs vary and those reservoirs are a separate part of the radiator and must be replaced if they don't hold pressure).
Where I would start is by having your mechanic do a chemical test at the radiator to identify a leaking cylinder head gasket. If that turns up positive there's no other remedy than new head gaskets. That's pretty common on any car brand today. If the test is negative we'll get to discuss other causes of overheating that are less serious. Be sure the electric radiator fan is turning on and the radiator cooling fins aren't plugged with a butterfly collection and aren't corroded and crumble easily.
Jul 5, 2013 at 1:34 PM
