2001 CHEVROLET CHEVY VAN Engine And Engine Coolingengine Problems

I TOOK MY 2001 CHEVROLET VENTURE TO DOAN CHEVROLET IN ROCHESTER NY BECAUSE I WASN'T GETTING THE PROPPER AMOUNT OF HEAT. THEY CALLED AND TOLD US THEY FOUND ANTIFREEZE IN THE ENGINE OIL. THEY SAID THEY HAD TO REPLACE THE REAR LOWER INTAKE GASKET THAT WAS LEAKING. THEY SAID OUR ENGINE WOULD SEIZE UP SOON IF WE DIDN'T GET IT TAKEN CARE OF. SO WE HAD THE WORK DONE FOR A BILL OF $640. WE HAVE SINCE HEARD FROM SEVERAL PEOPLE WITH GM PRODUCTS THAT HAD A SIMILAR PROBLEM RELATED TO ENGINE GASKETS. WAS THERE A RECALL I MISSED OR DOES GM JUST NOT THINK THIS IS A SERIOUS PROBLEM? IF IT HADN'T BEEN FOR THE LOW HEAT, OR IF THIS OCCURED IN THE SUMMER, WE MAY HAVE NOT FOUND THE PROBLEM AND SEIZED UP DRIVING 65 MPH DOWN THE THRU-WAY. A THREE YEAR OLD CAR SHOULD NOT HAVE BAD...