OVERHEATED ENGINE AFTER MECHANIC OPENED AND TOPPED OFF HOT SURGE RECOVERY BOTTLE WITH COLDER GM DEX COOL COOLANT & CREATED A SUDDEN AND ACCIDENTAL LOSS OF COOLANT. VEHICLE OVERHEATED WHEN AN AIR POCKET FORMED DUE TO LACK OF COOLANT IN THE ENGINE COOLING SYSTEM DAMAGED BOTH ENGINE HEAD GASKETS. FIRE POSSIBLE. *TR