Polyurethane is designed to last. It doesn't rot or deteriorate from oils, road salt, chemicals or atmospheric contaminates such as ozone or smog. That means our bushings will not deteriorate and cause mushy, uncertain responses when driving. Our components make a drastic improvement in the way your Jeep handles. This polyurethane mount controls driveline movement and is unaffected by oil and other contaminates. The stock rubber transmission mount will eventually get soft and deteriorate.