Detroit Cork/Steel Core valve cover gaskets are made from a premium cork rubber blend. The cork is then bonded to a steel core between the 2 layers of cork. This 5/16” thick gasket is impervious to oil, gas, methanol, or ethanol.
Detroit Rubber Coated Steel Valve cover gasket use a steel membrane that is put in an injection mold where pure virgin rubber is used to encapsulate the steel core. Multiple raised ridges are formed on either side to help the gasket seal to the surfaces of aluminum, steel, or cast iron.