There are times when the aggravation of trying to unseize a nut isn’t worth the time, or the inevitable is about to happen, so I simply glove up and grab the breaker bar and twist it apart. Other times I want to reuse the bolts and/or I would prefer that it didn’t break off inside a component. That’s when penetrating oil will be brought into action.
Just like everything else, there are a multitude of penetrating oils and similar products to choose from, all claiming that theirs is better than someone else’s and I have accumulated a small collection, so a year ago I decided to put all of them head to head in a test.
Preparation
To start off I needed a common denominator to work from so I purchased a selection of 3/8 inch nuts, bolts and washers. Each unit would be the same and included: bolt, two flat washers and a nut, all plain metal (no coating) and all torqued to the same value of 35 lbs. Before assembly all the pieces were doused in a container of acetone and let dry.
As I was going to test four products the line up went like this:
Batch 1: four bolts were assembled, torqued and set in one cup;
These four were pre sprayed with their individual product, assembled, torqued to 35 lbs, and then set individually in salt water that would evaporate and be refilled for one year.
Batch 2: four more bolts were sprayed with their product and then assembled, torqued and given their own cup marked with the product;
Batch 3: one was assembled, torqued then painted with Tremclad gloss yellow spray paint and placed with batch 1
Batch 4: one was assembled, torqued and also placed with batch 1
All four cups were now filled with a salt solution and allowed to dry out before refilling over and over again while sitting on the window ledge through a full season. The batches pre-coated were in separate cups to prevent cross product contamination; I figured the painted one (once dry) would not do this. For a variation, the fluid refill also used snow and that vehicle killer, brown salt sand slush combo scooped fresh from the bottom of my truck.
The test
After a year of babysitting these bolts it was time to clear off the window sill:
Batch 1: each unit of batch one was sprayed with its own product and let stand for 30 minutes then clamped in the vise and using a gauge torque wrench force was applied to see what pressure the nut would release or break.
Batch 2: each unit of batch two was placed in the vise for the same torque test (these were sprayed prior to assembly to see if the penetrating oil would help prevent rusting so no additional coating was given).
Batch 3: the lone painted one was only painted, not treated and was also placed in the vise for the same torque test.
Batch 4: a bolt that was exposed to the elements but not sprayed with anything (control test)
Some may recall me writing in a previous column, that threads should not be lubricated prior to torque as they will over tighten to the point of breaking. Well, that’s what happened here. When I was setting this experiment up, the first bolt that I treated and attempted to torque tore itself in half, the lubricant allowed the nut to be tightened onto the bolt to the point of destruction. I had to torque very slowly to a maximum of 35 lbs. which is not very high, but above that the bolt threads stripped. This was using a slow movement with a torque wrench; you can imagine what would happen with an air gun.
The results
Torqued to 35 lbs. the removal lbs. were:
Batch 1: bolts spayed and sit 30 minutes with product before disassembly:
•bolt1-WD40: 50 lbs
•bolt2-Stuff : 52 lbs
•bolt3-Krown Penetrating: 45 lbs
•bolt4-Mother Earth: 30 lbs
Batch 2 (pre sprayed with product prior to assembly)
•bolt1-WD40: 28 lbs
•bolt2-Stuff : 40 lbs
•bolt3-Krown Penetrating: 20 lbs
•bolt4-Mother Earth: 25 lbs
Batch 3 painted
Unscrewing the painted bolt shows the threads as clean as they went in, no rust at all.
-bolt 1-painted Tremclad: 30 lbs
Batch 4 (lone untreated bolt): 50 lbs
These are some interesting numbers and I thought they’d be closer all having the same environmental treatment. From the beginning I suspected that the painted bolt would do the best as it only stands to reason that if you keep the oxygen away from the metal, oxidation cannot occur so the resistance should not exceed the tightened torque. Slightly lower (30 lbs.) places it the same as using Mother Earth on a seized bolt.
As for pre-spraying I still don’t recommend it, if not only for the over torque situation but it allowed all but one to loosen off well under the 35 lbs. of tightened torque.
Of course there are other ways to loosen bolts, such as with heat. Sourced from a flame (torch) it can be very effective, not always an option (working around flammable products) and not always 100 per cent.
Another heating source is the mini inductor (electric) which creates a magnetic pulse causing the iron molecules to super-heat which can assist to release steel bolts, not 100 per cent, real expensive and they don’t work on aluminum hardware that is used in transmissions, transfer cases and aluminum/aluminum engine components to prevent dissimilar oxidation.
As for my test, the list is quite compatible. Some are better for the environment than others and prices are all close so once again, the choice is yours. When given the choice I prefer to paint my equipment and not wait until it’s so rusted that extremes have to be reached in order to disassemble.
A final note of caution: one should eat first when working with ‘stuff’ which is made from recycled restaurant fat fryer oils. After spraying the bolts I got so hungry I almost chewed my left arm off.
— Dan Kerr