Comparison of Penetrating Oils

zzvyb6 · Mar 6, 2014

Borrowed this from my windmiller's forum...

A study done by Machinist's Workshop magazine in their April 2007 issue looked at different penetrating oils to see which one did the best job of removing a rusted bolt by measuring the pounds of torque required to loosen the bolt once treated.

If the study was scientifically accurate, it turns out a home brew works best!

Here's the summary of the test results:

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 Automatic Transmission fluid (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. A local machinist group mixed up a batch and all now use it with equally good results. The home brew is Highly Flammable---Use Caution !!!

Note also that "Liquid Wrench" is about as good as "Kroil" for about 20% of the price.

J_J · Mar 6, 2014

zzvyb6 said:
Borrowed this from my windmiller's forum...

A study done by Machinist's Workshop magazine in their April 2007 issue looked at different penetrating oils to see which one did the best job of removing a rusted bolt by measuring the pounds of torque required to loosen the bolt once treated.

If the study was scientifically accurate, it turns out a home brew works best!

Here's the summary of the test results:

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 Automatic Transmission fluid (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. A local machinist group mixed up a batch and all now use it with equally good results. The home brew is Highly Flammable---Use Caution !!!

Note also that "Liquid Wrench" is about as good as "Kroil" for about 20% of the price.

This is the original mix called ED's red.

Ed's Red

nforktractor · Mar 6, 2014

I've tried them all at one time or another, except for the ATF-Acetone mix, Kroil Oil is the best I've used.

the old grind · Mar 6, 2014

I've preferred Kroil to Blaster for years but still use both. Trouble with Blaster happens with repeat applications when the volatiles evaporate and leave an oily film to block or dilute additional shots. I use Gibbs too, and it seems to be among the best, esp on the corrosion of black powder residue or on 'old mils' from WWII on back.

IMO, the worst thing about Kroil is having it seep thru' the bottom seam of the can if bounced around on hard surfaces (.. if not the gawdawful smell). I've got a gallon can under my reloading bench and am scared to move it far when topping up the 8oz cans that don't leak already. :grumpy: If it's good on ferrous rust it seems even better on bolts frozen into aluminum parts. I guess the white crud is more porous and it seems to soak deeper quicker.

The one place nothing seems to work for me is the spline on my Terramite's steering wheel. Maybe I should have tried the acetone/ATF mix already. :mur: You can bet I will now. Thanks for the tip/reminder! (I'm off to my 'alchemy lab' today...)

art · Mar 6, 2014

I haven't used the Kano stuff do to the cost but in the past there stuff was always good. The others we have tried, of the rest the acetone/atf is the best. Seen parts that have been heated to remove by customers and virtually fell apart with the mix.

DFB · Mar 6, 2014

Seems WD now markets a penetrating oil blend specifically for use on rusted parts. Anybody tried it?

Best Penetrating Oil & Rust Inhibitor Spray | WD-40 Specialist

DJ54 · Mar 6, 2014

I've used them all too. Still have about a pint left in a gallon can of Kroil, that's got to be 30 years old. No doubt it's good stuff. But two years ago, I saw where Soundguy talked highly of the Acetone/ATF mix, and decided to try it. I'm here to tell you it is the best thing I've ever used..!!

I usually try to look things over well ahead of a planned tear down. I used the 50/50 mix on an old manure spreader chain adjustment eye bolt. I put it on 3 days ahead of the tear down. I gave it a small shot every morning on the way to the barn. This bolt had scaly rust on it, and I did hand wire brush the rough stuff off after it had soaked the 3 days. Once I broke the double nut loose, it turned so easy, I ran the nuts off with my fingers. I also used it on my 40's vintage wood/coal stove I rebuilt for the new shop. Some of the soft stove bolts twisted off in the cast iron portions. I was able to lay them down, so as to hold a small puddle of the mix. Within 5-6 hours, I center drilled it with a tiny drill bit, and used the smallest easy out I had, and they backed right out. You always think the first one may be a fluke, but when they all came out easily, it made me a believer..!!

You'll just have to try it yourself to believe how well it works.