Machinist's Workshop magazine actually tested penetrates for break-out torque on rusted nuts. They arranged a subjective test of all the popular penetrates with the control being the torque required to remove the nut from a "scientifically rusted" environment.

*Penetrating Oil and Average Load*

Nothing..................... 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. Note also that "Liquid Wrench" is about as good as "Kroil" for about 20% of the price