Hylomar is a non-hardening polyurethane based compound which is impervious to gasoline, oil, or any motorcycle related fluid. Use as a gasket maker, gasket dressing, or thread sealant. Hylomar goes on the surface like a jelly and in just minutes, turns to a putty and is ready for assembly. Because of its Velcro like ability, it can be reused and reassembled. Hylomar is a non-hardening polyurethane based compound which is impervious to gasoline, oil, or any motorcycle related fluid. Use as a gasket maker, gasket dressing, or thread sealant. Hylomar goes on the surface like a jelly and in just minutes, turns to a putty and is ready for assembly. Because of its Velcro like ability, it can be reused and reassembled.