Valve cover gaskets keeps the cylinder head protected keeps oil from escaping from your engine. Although the valve cover gasket is well protected from the top and bottom, it is very delicate and prone to damage from the sides. Over a period of time the gasket becomes brittle and will crack due to exposure to dirt, debris, heat and other elements. When this occurs, the gasket can lose its integrity and leak, potentially causing cosmetic issues like leaking oil, or drivability problems and reduced engine performance. Some of the symptoms of a failing valve cover gasket includes oil leaks, burning oil smell etc.