Cadillac Repair: cadillac, bolt holes, coolant system

Question
OKAY I HAVE A 1994 CADILLAC CONCOURS WITH A V8 NORTHSTAR ENGINE I JUST BOUGHT THIS CAR IN JANUARY I HAVE BEEN HAVING OVERHEATING PROBLEMS. ONCE THE WEATHER BEGAN TO WARM UP THE COOLANT IS BOILING AND COMEING OUT OF THE OVERFLOW HOSE AFTER ABOUT 5 MILES. I HAVE HAD THE COOLANT SYSTEM REWIRED, THE THERMOSTAT REPLACED TWICE, THE HOUSING, AND REPLACED ALL THE HOSES. WHAT ELSE COULD POSSIBLY BE MAKING MY CAR OVERHEAT?

Answer
This engine is very prone to having leaking head gaskets due to the metal head bolts stripping the aluminum threads in the engine block. The only cure is to heli-coil the bolt holes and install new head gaskets and new head bolts.

I have heard of some people who tell me that they resolved their overheating issue by installing the SEALING PELLETS into the radiator of which you can get at any auto parts store.