The downstream O2 sensor heater died. Last night I liberaly spread Kroil on the sensor. This has an O2 extension, so I spread on both ends of the extension. In the morning handed the new O2 sensor to my mechanic and asked him to keep the extension on the car and replace the sensor. Knowing Kroil's miracle powers, I hold him it should come off easy. As soon as he puts a wrench on, the extension breaks off and he hands me the old O2 sensor along with the half of the extension to me. He then tries to take off the extension end still attached to the catalytic converter. It is not budging at all. Out comes his blue wrench, broken extension is glowing red and it comes out without any more struggle. After bringing old sensor at home I decided to try it myself to see if I can separate the sensor and the extension. I had O2 socket with a slit in it, so I tried to hold one end with a breaker bar and bang the other end with C3 lithium 19.2 impact. It does not budge at all. Suddenly the battery goes complete dead. Putting it on the charger reveals that something has gone wrong with it :-( Took the battery and put it in the freeze for five minutes. Now the charger has at least accepted the battery. We will see what happens in an hour. The stainless steel O2 sensor extension is on the way and I will be making another trip to the garage to install it. I am extremely disappointed with Kroil. I have another project to remove and clean the EGR valve. The bolts are right staring at me but I see lot of rust. I have sprayed with Kroil many times but I am still reluctant to touch them, especially with today's major fail.