This is a followup to the article Dogdays posted.
I've highlighted the things I think are helpful clarifications.

Quote:
Machinist's Workshop V20 number 2, April/May 007, page 35
Article: “Testing Penetrating oils”
This reports a test of penetrating oils where they measured the force required to loosen rusty test devices. The details reported here were validated by the original article author. He also added some details on the methods.
You must buy the issue if you want to see how they did the test. The back issue is available for purchase.
The table below extracts the results table The lower the number of pounds the better. Interesting that a simple mix of acetone and power steering fluid (PSF) works the best!

Penetrating oil Average load Price per fluid ounce
None 516 pounds
WD-40 238 pounds $0.25
PB Blaster 214 pounds $0.35
Liquid Wrench 127 pounds $0.21
Kano Kroil 106 pounds $0.75
PSF-Acetone mix 53 pounds $0.10 (50/50 mix)

Notes from original article author:
1) These are loads required to free the test piece after 8 hours of immersion in penetrating oil. This is probably not representative of a quick squirt just before a wrench is applied.
2) The original article states ATF was used in the DIY mix. It was actually PSF. I corrected the table to reflect this.

© Copyright 8 February 2008, 63Avanti@sterkel.org
Permission to print and post on the internet in this form received from the author
8 February 2008


Avanti.org is gone. frown Maybe its been saved in archive.org I haven't looked.
There are various power steering fluids so we can only guess that the one used was one with low viscosity and high detergents. shruggy

My own experience has been that PB Blaster is good when applied the day or days before. Even better reapplying each day. I like it for situations where impact is not possible or seems inappropriate. Removal usually requires slow steady force. Stuff doesn't 'break free' but feels more like a fastener with interference fit.
Kroil seems better for last minute use. Sili-kroil seems to help more in making it easier to turn once the bolt has broken free.
I agree with those that like the sprays specifically for freeing equipment