Here is a tip from member Rich Gregory on Penetrating Oils
Machinist's Workshop MagT recently published some information on various penetrating oils that I found very interesting. Some of you might appreciate this. The magazine reports the break out torque values on rusted nuts using the tested penetrating oils. Results are below, as forwarded by an ex-student and professional machinist. 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 oils ....Average torque load to loosen*
No Oil used .................. 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 is a "home brew" mix of 50% - 50% by volume automatic transmission fluid and acetone. Note this "home brew" released bolts 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 almost as good as "Kroil" for about 20% of the price! Steve from Godwin-Singer says that the ATF*-Acetone mix is best, but you can also use ATF* and lacquer thinner in a 50-50 mix.
*Automatic Transmission fluid