That Permatex Ultra Copper High Temp RTV is the Best Stuff to use as Grumpy said 2 years ago to me. #2 on my list is Permatex Ultra Grey RTV. Everything else gets a coat of Permatex Aviation gasket cement. Pontiac V8 engines I Edelbrock Gasginch. Fel Pro Race Head Gaskets I like putting on dry. Grumpy Likes Ultra Copper spray on headgaskets. I use It on LS headgaskets to.