I can not get the oxygen sensor after the main cat off. I have tried multiple applications of penetrating oil/liquid wrench without any luck. I have the cat off the car and put the cat in my vise, and using an extension bar on my socket to increase the torque to the point that I tore my vise off my work bench. I reattached the vise to the bench with stronger bolts and now I am lifting the bench off the floor. The sensor doesn't appear to be rusted nor does it appear to be cross threaded. Any suggestions on a way to loosen the oxygen sensor would be appreciated.