I still have most of a case of PB Blaster they sent me for free for pointing out an error on their label. I have CRC Freeze Off but have not tried it.
I need to get some black iron pipe off my propane generator so I may be using some of these products soon.
My Dad at times would connect his carbon arc torch to his welder and put the carbon rods directly on the surface you want to expand with heat. You make that surface be the conductor for the electricity. It heats up quickly and the rust insulates it from the inner surface you do not want to expand.
I read somewhere a while ago, some test against all of the penetrating oils and I believe liquid wrench came out on top. I use either that or PB Blaster.
Used them all . Depends what you are using it for. My ratings for nuts and screws
1)90% trans fluid + 10% acetone - for soaking old parts
2) p.b. blaster- the smelly one
3) kroil- old outboards - aluminum
4) zep
5) liquid wrench- for plumbing parts - soft metals
6) break away
7) deep creep- hard to get too bolts
8) crc - oil
9) wd-80
I keep a gallon of p.b. nearby and fill a 12 ounce spray bottle with it. Works much better and cheaper than spray cans .
Haven't tried many but Seafoam deep creep really does 'creep'. Has worked well.
Also have CRC freeze-off and it worked great on exhaust flange bolts.
AeroKroil is like 12 bucks here at Napa IIRC.
Well I do not seem to have much luckwith penetrating oils. A torch seems to work best for expanding and then a little pounding with a hammer and a good impact wrench. And still have sheared bolts and the like.