Permatex OPTIMUM BLACK Gasket Maker combines maximum oil resistance with high flexibility. Many modern engines now involve gasket joints with dissimilar materials including plastic-to-steel and aluminum-to-steel. As the engine heats up, these components have different rates of expansion and contraction. Combine this with lighter weight and thinner materials, the demand on a gasket to perform at optimum levels has never been greater. The strength and flexibility of OPTIMUM BLACK meets and exceeds the specification to reliably seal lightweight and high-performance assemblies. It is sensor safe, low odor and non-corrosive with resistance to oil, shop fluids and thermal cycling. OPTIMUM BLACK is one of the most advanced, high flex, maximum oil resistant RTV silicone gaskets available.