Gene D. writes: “A couple of years ago, I had to replace the exhaust pipe on my car.  When I was removing the old pipe, I discovered that the bolts holding the pipe to the catalytic converter were completely rusted, so I soaked them down in WD-40 and waited half an hour.  When I tried to remove them, all I succeeded in doing was stripping the nuts almost completely round.  I went to the auto parts store to see if they had replacement bolts and nuts in stainless steel.  I explained my situation to the salesman there and asked him for advice on the best way to remove the existing bolts.  He pointed me to a can of PB Penetrating Catalyst and guaranteed me that it would do the trick.  I was a bit skeptical, but it sounded better than cutting the bolts off, so I went home and sprayed down the nuts and bolts and waited about 5 minutes.  I was able to easily remove the nuts using a pair of vice grip pliers.”