The turbo heat shield is composed of two layers of metal and oil sits in between from the previous leak. If you replace the N54 valve cover gasket, make sure you allocate some time to remove the shield, heat the shield on a stove and remove all oil before placing it back, or you will agonize over the valve cover still leaking and maybe even replace the gasket again or even the cover without being necessary. Ask me how I know :)
