I have a 2002 buick century custom. Apparently there is a problem with the antifreeze that was used in these vehicles. What do I need to do to repair the damage caused by this problem

The dexcool coolant in these vehicles, was designed to fight coolant seepage through the porous aluminium parts. It is still the recommended coolant. It does, however, tend to clog systems. Mixing other coolants with it tends to make this problem worse. Flush your system, be mindful of leaks , and stick with what those pesky engineers recommend. Any warranties you may have left will require it!

You need to drain the old antifreeze and flush the entire cooling system with a commercial product such as Prestone Super Flush. After flushing according to the directions on the product you will want to fill the cooling sysstem with plain water and let it circulate through the system. Drain the system again and repeat the process until the water is clear of any antifreeze. Refill the system with the proper mixture of antifreeze. Make sure you use a quality antifreeze that is compatible with your make and model of car. The auto parts store personnel can help you select the right antifreeze. DO NOT refill it with Dexcool. That is the antifreeze that GM put in originally that is causing the problems. Dexcool not only forms a gummy sludge in the cooling system, it also attacks certain gasket materials and causes coolant to leak into the engine. Hopefully, this hasn't happened yet.