RedY2KS2k

Kroil has a good reputation among the old-car crowd. I've never tried it, but from what I've read it's probably the cream of the crop.

PB Blaster was highly recommended by some people whose opinions I value. It's available over-the-counter at Advance Auto Parts, etc. I bought it, but never used it.

I use Howe's Multi-Purpose because it works pretty well and I have a gallon of it. Literally. My former employer wholesaled it in 4 or 6 (I don't remember which) gallon cartons; they sold us the damaged gallon jugs when one leaked all over the others.

The CRC Freeze-Off intrigues me, but I've never tried it. I suspect that the freeze action can be replicated by using a hammer or hammer/punch to generate some vibration in the fastener.

I've read that brake fluid works, but it destroys paint so I wouldn't recommend it unless you're stranded.

Vanishing Point

ATF and Acetone is the best penetrating combo. assuming it's not on a painted surface.

Interesting stuff to my friends that turn a wrench!

Machinist's Workshop magazine actually tested penetrants for break out torque on rusted nuts. Significant results! They are below, as forwarded by an ex-student and professional machinist, Bud Baker.
*Don't forget the April 2007 "Machinist's Workshop" magazine comparison test.*

*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. *
*Your experience may vary, etc., etc.

Zoomie

really interesting. it isnt often a thread like this ends up with actual testing and numbers, ha!

ispkarl

BG in-force !! is the best !

chuhsi

i love pb blaster

dammitjim

PB Blaster, breaker bar/extension, tapping with a hammer, tightening then loosening, torch, cut-off wheel, C-4, Chuck Norris

irv_usc

Interesting to see the numbers. I guess what a lot of people do is neglect the waiting time to let the oil penetrate the problem area.

Of that list, I've only used WD-40 and PB Blaster. Interesting to know that they are almost the same. I generally spray a part and wait at least half an hour before trying to break it loose again.

viets2000

Agreed. 1:1 Acetone and ATF All the way. Otherwise, PB blaster is cheap and easy to find.

babowc

torch+penetrating oil.

heat it up, then spray the oil.
it'll seep in and voila.