Driver's side O2 sensor is in so tight that the O2 sensor socket just rounded off the hex-head. 8P I tried to twist it out with Vice-Grips but that just broke the top off the sensor. So I'm about to hose it down with WD-40, then go to the hardware store to buy a longer ½" drive extension and try to take out the adapter thing that has a bigger hex-head. (sigh) (grumble)