steel shim head gasket

steel shim gaskets crush and then they are done. if you reinstall them, they need the copper coat or silver paint or whatever. The retorque on a shim gasket is the bolt stretch as you cant compress a steel shim once its used, as its flattened from the first torque. Composite gaskets or modern style sometimes say retorque hot but the Felpro no-retorque are crush style around the cylinders (fire ring). My Mazda says retorque at every valve adjustment (6,000m).