This is from another car messageboard:

Some of you might appreciate this. Machinist's Workshop magazine tested penetrants for break out torque on rusted nuts.

They are below, as forwarded by an ex-student and professional machinist, Bud Baker.
They arranged a subjective test of all the popular penetrants with the control being the torque required to remove the nut from a "scientifically rusted" environment.

*Penetrating oil ..... Average load*
None ...................... 516 pounds
WD-40 ................... 238 pounds
PB Blaster ............... 214 pounds
Liquid Wrench ......... 127 pounds
Kano Kroil .............. 106 pounds
ATF-Acetone mix.......53 pounds

The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic transmission fluid and acetone. Note the "home brew" was better than any commercial product in this one particular test. Our local machinist group mixed up a batch and we all now use it with equally good results. Note also that "Liquid Wrench" is about as good as "Kroil" for about 20% of the price.

 

wow thats awesome information to know. i will just get 2 bolts and replace everything.

 

If you are replacing all of the bolts, you'll need three

 

5 if you're doing front and rear of the cat...

 

yea, the rear bolts came with the test pipe but not the ones that attach it to the header.

 

What are you hoping for from fitting a test pipe?

 

just to try something new. i got a good deal, remove the cat, change the smell of the exhaust

 

so i tried it again today, and again the same issue. i got the new bolts on from the cat to the header, but the bolts from the exhaust to the cat wont budge. i used another can of anti-sieze and i actually broke my socket wrench. it wouldnt even break loose with my own breaker bar.

any suggestions? the only thought is to take it to a shop (it needs to go there soon anyway) and have them take the bolts off.

 

Ifd you have a compressor, a air gun will break those free. If you have to go to the shop anyway, have them loosen it up for you. Better yet, just have them replace them.