Best Penetrating Oil

Kind of surprising, but that mix (50-50) is what I use.
Word of caution - don't use a foam cup to mix it in. (Yeah, don't ask me how I know this)  
I mix mine in a glass jar with a good sealed lid - it does loose its effectiveness after time - it's best to mix up a small "fresh" batch for best results. I then pour it into an ALL metal squirt can to apply/use.


April 2007 "Machinist's Workshop" magazine comparison test wrote:

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 Average load Price per fluid ounce
None 516 pounds ------
WD-40 238 pounds $0.25
PB Blaster 214 pounds $0.35
Liquid Wrench 127 pounds $0.21
Kano Kroil 106 pounds $0.75
ATF-Acetone mix 53 pounds $0.10 (50/50 mix)

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.