Al,

The best penetrating oil as discussed previously on the list is ATF mixed 50/50 with acetone.

 

Apply this and while it soaks, put ice on the O2 sensor, then heat the exhaust with a torch.

Cut the wire off the O2 sensor and use a long impact socket and driver to remove the sensor.  Next time use antiseize on the threads.

 

Bill B

 

 

After about 130 hrs my O2 sensor seemed to be getting a little sluggish; so I decided to replace it. I put a wrench on it and unable to budge it.  A bigger wrench and still no luck – getting worried about cracking the weld around the bung, or some other damage.  Any ideas about getting that thing loose?

 

I didn’t put anything on the threads when I put it in – perhaps next time; but what?