I thought PB Blaster was one of the best penetrates until using Kroil then I read this, never would have guessed ATF and Acetone would prove better .....


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.

 

I've spoken to many mechanics, and they all swear that the Mopar brand rust penatrent is the best they've ever used.

 

I will try that the next time I require some help on a nut.
DO NOT get this on paint as it will strip it pretty good.