What's the best penetrating oil?

Machinist's Workshop magazine tested penetrants for break out torque on rusted nuts. 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. The results are as follows;

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.

I have tried it and it works great.