Found this in Engine Builder online:

What’s the Best Penetrant?

A recent online article provided some information on various penetrating oils. A subjective test of all the popular penetrates with the control being the torque required to remove the nut from a “scientifically rusted” environment resulted in the following numbers.

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 was a “home brew” mix of 50% – 50% by volume automatic transmission fluid and acetone. It has been said that lacquer thinner may be used as a substitute for acetone.

From: Engine Pro Technical Committee with special thanks to Machinist’s Workshop Magazine (www.machinistsworkshop.net) and Bert Hitzing.

R.