I HAD BEEN LOSING COOLANT (2 QUARTS IN 4~6 WEEKS) WITHOUT SEEING ANY SPOTS ON GROUND OR COOLANT ABOUT ENGINE / RADIATOR. WHILE DRIVING, EXPERIENCED RELATIVELY SUDDEN LOSS OF POWER, MIL LIGHT CAME ON, COULD NOT DRIVE GREATER THAN 60 MPH, VERY POOR OPERATION AND ACCELERATION. DEALER (SUPERIOR BUICK, DEARBORN MICHIGAN) DIAGNOSED PROBLEM AS BLOWN HEADGASKET. I SUBSEQUENTLY HAD ENGINE REMANUFACTURED UNDER DEALER PREMISE OF HEAD GASKET, ONLY TO FIND THAT THE UPPER INTAKE MANIFOLD HAD FAILED AND ALLOWED COOLANT TO PASS INTO INTAKE PASSAGES (REFERENCE GM SERVICE BULLETIN 010601007, AND ~7A). I WAS NEVER INFORMED OF THESE BULLETINS BY THE DEALERSHIP, BUT THEY ARE 2 YEARS OLD.*AK