Penetrating oil
Machinist's Workshop magazine actually tested penetrates for break-out torque on rusted nuts. 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 and Average Load*
Nothing..................... 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. 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
95 E34 530I V2.37
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