Machinist's Workshop magazine actually tested penetrants for break out torque on rusted nuts.
Significant results!

*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.*