I used about everything over the years on the race cars, black RTV, 3M yellow glue, contact cement, I glue it down on the vlave cover side, with nothing on the head side, and install it back on the head with the valve cover bolts for the glue/silcone to cure. If you using the alloy valve cover that has very little to keep the gasket located, I like the 3M glue or contact cement over silicone products