Run the newer Fel-pro's. Electrolysis from dexcool and some other green glycol based coolants is what is causing it. You will do much bettr with the newer style gasket. And go sparingly with the silicone. No plugged radiators and thermostats. As a note for all interested, use a digital DVOM and test the coolant to check on condition of coolant. 300 milliamps is max and at that time you starting to get excessive breakdown in the cooling system of parts and gaskets.