Tips & Tricks

Best Penetrating Oil: High-Quality Products for Affordable Price!

Penetrating oil is a liquid used to help release mechanical parts that have stuck due to various reasons, the most common being rust. Penetrating oils are made up to two chemicals, one to react with the rust of other corrosion elements and the second is oil based on coating the surface of the part allowing it to slide or move easily.

Many penetrations are used for more than one purpose, some to reduce sticky hinges, others to clean and protect greasy ferrous based tools and equipment. These oils come in two forms, a free flow can and a pressurized aerosol container.

List of Top-Rated Penetrating oils

Product ImageProduct NameApplicationTypeMore Information
1. Liquid wrench penetrating the oil1. Liquid wrench penetrating the oilAerosolStandard PenetrantMore Information
2. Kroil penetrating oil2. Kroil penetrating oilDripStandard PenetrantMore Information
3. Knock'er loose3. Knock'er looseAerosolStandard PenetrantMore Information
4. PB blaster penetrating the oil4. PB blaster penetrating the oilAerosolStandard PenetrantMore Information
5. WD 40 penetrating the oil5. WD 40 penetrating the oilAerosolStandard PenetrantMore Information
6. Kano Aerokroil penetrating the oil6. Kano Aerokroil penetrating the oilAerosolStandard PenetrantMore Information
7. Gibbs penetrating oil7. Gibbs penetrating oilAerosolGun PenetrantMore Information
8. Zep penetrating oil8. Zep penetrating oilAerosolPTFE PenetrantMore Information
9. 3 in 1 oil9. 3 in 1 oilDripMulti-Purpose LubricantMore Information
10. Royal Purple10. Royal PurpleAerosolStandard PenetrantMore Information
11. CRC penetrating oil11. CRC penetrating oilAerosolFood Grade PenetrantMore Information
12. Nuts off penetrating the oil12. Nuts off penetrating the oilAerosolCryo PenetrantMore Information

It is not advisable to use penetrating oils as lubricants for two main reasons. The first reason is that the oil is in fact made up of a volatile liquid that is combustible and corrosive. The second reason is that the percentage of oil can be extremely low and will dry up fast when used as a lubricant and not a releasing liquid.

In this list, I present to you the best penetrating oil for rusted bolts, these come in a variety of applications including penetrating oil spray and free all penetrating oil bottles. Since I will be looking at a variety of applications, you will find her also the best penetrating oil for the seized engine, the best penetrating oil for seized bolts and the best-penetrating oil for rusted nuts. I also include a number of options such as the best penetrating oil for aluminum, or for food processing applications.

Take note that penetrating oil is used in many applications globally, as such, it is used to unstick rusty components, as well as relieve sticking components in machinery that can be found in all kinds of machines including the pharmaceutical and food industry sectors. As such, some penetrating oils need to be 100% safe for human use, and not be allowed to contaminate delicate ingredients. In this review, I also present one such oil as a suitable application for individuals seeking a safe penetrating oil solution.

Other applications are for the gun sector, where specific ingredients are used to apply to guns of all types, ranging from handguns to AR and rifles. Again, gun penetrants have a different composition from standard block penetrating oil solutions.

Now let’s take a look at the list of the 12 leading best brands of penetrating oil solutions on the market today.

The Best Penetrating Oils Reviews

1. Liquid wrench penetrating the oil

LIQUID WRENCH® lubricating oil is a leading brand that provides many solutions for different applications.


This is the penetrating oil variant of Liquid Wrench and is formulated to penetrate any stuck or rusty connection between two metal, plastic or painted surfaces. To fully utilize this penetrating oil you need to soak the parts using the spray on hose attachment, and let the stuck parts rest in the soaked state for a few hours. With rust, its best to just let it stand for even a day, and after the first initial spray, add another spritz of Liquid Wrench penetrating oil about 2 hours later to provide an extra strength performance.


2. Kroil penetrating oil

Kroil is the proprietary name for all Kano Engineering products. Kano Engineering is a reliable and well-respected company that has been providing various penetrating oil solutions to the USA market for over 80 years.


This is Kano’s Kroil, penetrating oil. This penetrating liquid is extremely powerful and has been around before most others were even thought of. The Kroil product comes in a number of sizes; this one is their 8 flow ounce can. You apply it by either pouring it over the stuck objects or use a syringe 9 standard common all garden syringe) to spritz onto the stuck parts.


3. Knock’er loose

CRC nock’er Loose® is a petroleum-based medium viscosity penetrating oil that is used to relive stuck objects and apply a thin lubricating coat.


Knock’er Loose® is oil based with a solvent to provide perfect rust removal properties as well as act as a lubricant for on the spot unsticking. This aerosol version comes with a low viscosity with is perfect for spraying over and into the tightest of areas.


4. PB blaster penetrating the oil

PB B’Laster has been around since 1957. This is one of the three leading companies in the US for penetrant oils, and this is their original model.


When it comes to proven quality of performance, P’Blaster has been and is used by a majority of the market and contends with Kroil, CRC, 3M, and WD40 as a leading brand.

This is a no-nonsense penetrating oil that is used by millions and works. It’s a simple spray it on and leaves to penetrate and soak. Once done, the use of some basic torque will unscrew any rusted bolt or contact friction surface.


5. WD 40 penetrating the oil

WD40 did for the penetrating oil industry what Uber did for ridesharing. It made it global. However, WD40 is not really an oil; it’s more of a solvent that helps fight rust and opens stuck components.


WD-40 stands for “Water Displacement formula 40,” and while it is the most popular brand, giving its name to synonymize an entire industry, it is not a lubricating penetrant. This product I used to fight stuck components, as such, it’s a penetrating solvent that provides a small film of oil to help with the initial release of the components.

This is the WD-40® Specialist® VOC compliant spray. It is designed with their proprietary Blu Torch® Technology. Which is a fancy way of saying we won’t tell you our ingredients, but the damned thing works great cos we gave it a fancy name?


6. Kano Aerokroil penetrating the oil

This is another Kano Engineering product that doesn’t hide behind fancy names; it just delivers straightforward penetrating performance.


This is Kroil in an aerosol spray can, which makes it much easier to apply. Kroil has a few alternative delivery options, and one of them is their aerosol spray Kroil penetrating oil. It works perfectly well and uses standard CO2 to deliver the penetrant for a perfect performance operation.


7. Gibbs penetrating oil

GIBBS™ Brand penetrating oil has been around since 1969 and was the development of a Harley Davidson mechanic named Paul Gibbs.


With 50 years of success, Gibbs has been a leading light in the bike industry, and used in all kinds of applications that includes protecting electrical connections from oxidation, loosen corroded components and treating bare metal surfaces. Gibbs is also a favorite in gun care maintenance and while it does portray one solution for all, is a reasonable penetrating solution.

Personally, I don’t go for brands that sell me one solution for all product, but in this instance, it does work well on many stuck parts, and as a penetrating oil solution is up here in the top 12.


8. Zep penetrating oil

ZEP started out as a hygiene solution company back in 1937, and is the owner of a number of brands including RainX, today it is a conglomeration of chemical companies that provides a comprehensive range of products including the ZEP45 penetrating oil


ZEP 45 contains Teflon (PTFE) which is used as a solid-state deposit to coat the internal surfaces of the stuck components, providing a solid state lubrication performance with the solvent liquids that remove rust and water.

This is a classic penetrating formula that works, and includes a PTFE and is a Nonflammable 4N1 Formula with no Ozone depleters.


9. 3 in 1 oil

3 in One is the oldest penetrating oil company in the USA and maybe the world, it started out in 1894 and comes in the classic drip can applicator that many factory and maintenance workers have grown up with, through two world wars.


3-IN-ONE® is the can everyone’s father, grandpa and local bike mechanic had on hand in the garage. It stands there on the windowsill or in a dusty corner just waiting to be used. The 3 in o1 stands for penetrating, lubricating and cleaning, and it works.


10. Royal Purple

Royal Purple Maxfilm is a synthetic solvent oil compound that comes with their proprietary Synerlec® additive technology and uses a CO2 propellant.


I won’t explain all the fancy names, I just go for the jugular, and that’s what this product does, it goes from the penetration and easing of stuck parts. You spray it on, wait the time needed and then unstick the parts. This product is not a lubricating oil, it’s a penetrant solvent oil compound and works with all materials including aluminum that requires a thin lubrication coating to help ease the stuck surfaces.


11. CRC penetrating oil

This is the CRC Food Grade penetrating oil used for industrial applications that require a non-toxic approach to penetrating solutions.


This product has been designed by CE+RC for use in the food processing industry which includes processing plants to kitchens.

As such, it is designed to work with Food Processing Equipment With Perma-Lock® Flammability Class – CPSC using a mineral oil with a Spec Gravity Concentrate of 0.82 and is safe to use on most plastic surfaces. For full specifications check out the link.


12. Nuts off penetrating the oil

Bull’s Eye products have a different approach to penetrating oil solutions, it provides a fast cooling effect that exhibits freezing properties to contract the metal components so that an air gap allows the penetrating solution to work easier on the internals.


Nuts off use both a fast freezing chemical reaction and their XA-17™ Rust Eating Technology which is a fancy name for some chemicals that dissolve rust.

The concept is not to break the parts as you would with liquid nitrogen, but to create a larger gap between the components, even separating them. This extra gap would facilitate a larger penetrating oil surface and also help dissolve any internal rust. As such, the penetrant oil is a cryo-oil solution and not a standard penetrating solution.

What this product claims to do is to instantly freeze the applied materials down to 45 degrees below zero in less than five seconds. This rapid freeze leads to microscopic cracks in the layer of rust allowing the penetrating oil to wick directly into the rust by capillary action.

Bottom line, it will freeze your balls off if you are stupid enough to spray it on them, so don’t.


Where to buy Kroil penetrating oil locally

Kroil can be bought online directly via their site, or online via numerous e-commerce sites. I can also be bought locally in brick and mortar locations since Kroil and Brownells has a combo deal with a can of Kroil plus a jar of J&B bore cleaner. This means that anywhere you buy Brownell’s you can buy Kroil.

What is penetrating oil?

What a good question, I am glad I asked it. Penetrating oils are in fact more solvent than oil and are chemicals used to provide a very low viscose solution that can seep into the slightest of cracks, especially rusty ones. A good penetrant will actually reduce rust/paint/corrosion into a liquid sludge as well as provide a lubricating surface to the metallic components thereby allowing you to apply torque to release them.

As such, the focus of a penetrant is three: penetrate tight locations, apply a viscous surface and remove obstacles that constrict movement. The most basic performance is for iron-based surfaces that have rust, from there, penetrants expanded in use to allow of all kinds of metallic surfaces, including aluminum that tends to stick like glue to another aluminum surface, in this case, you only need to lubricate the two surfaces. As well as painted, glued and varnished surfaces that require dissolving the restricting materials to allow light torque.

The basic functions in detail are:


The product must be so lightly viscous that it will be able to penetrate even the tightest of cracks, as such, the actual products performance is graded first on its ability to penetrate and then on its ability to clean the surfaces in combination with lubricating them for easy torque. However, before the cleaning agents and the lubricants can work, the liquid has to penetrate.


This requires that all products have some form of lubricating material, be it liquid mineral, biological or solid state materials that cover the surfaces providing a smooth application to enable movement. Penetrating oils are not lubricants, they do not replace lubricating oils, the lubricant in the penetrant mixture is for application purposes only, and once applied will require to be cleaned off and lubricated properly.

Cleaning Agent

The main purpose of the penetrating solution is to clean the restricted surfaces; this can include rust, paint, glue, varnish, and other particulates. The cleaning agent acts as a solution that dissolves the restricting materials, allowing the surfaces in contact with each other to be freely moved using torque.


Straight Oils

These are undiluted nonemulsifiable solutions that are composed of base mineral or petroleum oils; some of them contain polar lubricants such as fats, vegetable oils, esters, or extreme pressure (EP) additives such as chlorine, sulfur, and phosphorus.

Water soluble/Emulsion Fluids

Water soluble and emulsion fluids are highly dilutable with water and have a low concentration with high water content fluids (HWCFs). These solutions contain a soluble oil to act as an emulsion when mixed with water. As such, these are not used on ferrous metals, since they encourage rust.

Synthetic/Semi-synthetic Fluids

Synthetic and semi-synthetic penetrants and penetrating oils are made from mineral bases products such as silicone, polyglycol, esters, diesters, and chlorofluorocarbons (CFCs). These products have the highest fire resistance but are also the most expensive.


There are many alternatives to penetrating oils, and these include homemade solutions that are made from a solvent such as acetone (nail polish remover) and any cooking oil. There are also additives to oil that provide similar solutions but are more for preventative maintenance rather than on the spot solutions to stuck components.

For instance; extra pressure (EP) additives are used by adding them to improve wear resistance and lubricate metal surfaces. These products include chemically active agents such as sulfur, phosphorous, or chlorinated compounds. The agents react with metals in a high-stress environment forming a chemical coating such as sulfide, chloride, or phosphide, and these coatings act as a solid-state lubricant, allowing the metal to turn with slight torque.

Corrosion inhibitors are additives that prevent the onset of corrosion, and when applied before the onset of corrosion adsorb to the surface through the electrostatic forces between the molecules and treated surface or react with the surface to form a passive layer coating.

Micro dispersants come with solid state particulates such as polytetrafluoroethylene (PTFE), graphite, and molybdenum disulfide or boron nitride. These particulates are part of the solution and coat the surface acting as a lubrication bridge between the two surfaces.

How to select

As you have read, there are many options to choose from, and each one is designated to focus on a specific set of issues. When you need to choose with penetrating oil solution to apply you need to configure into the equation the following indicators.


This where the liquid evaporates into a flammable gas at its lowest natural temperature. Since most penetrating oils come with a VOC, usually an acetone type substance, selecting a penetrating oil for flammable applications becomes a major concern. Especially where there is a lot of electrical circuitry that provides arcing. Other considerations include the location of application, such as hot machineries such as those found in foundries or kitchens.

Make sure that when you select the penetrating oil, you don’t end up blowing yourself up.

Operating temperature

This is the mean temperature where the penetrating oil performs at its peak. As such, you need to consider the working environment you are in, as well as the environmental temperatures.


ider that a cryo penetrant will not work well in freezing winter conditions, where a blow torch might be better.

Dielectric strength

This is the maximum voltage field the fluid can withstand before an electrical breakdown occurs. As such, penetrating oils for electrical applications must come with an extremely high dialectic strength or the conductivity will destroy the load.

Water displacement

These solutions specialize in displacing water from a surface based on wetting or surface energy characteristics. As such, they are not standard fluids, but have a specific purpose, and can be used in wet or humid atmospheres for their specific characteristics. In other words, WD40 might work perfect in Miami, but not as well in Nevada.



This is the military grade specification requirements from penetrating fluids, and if a product has this spec. you know it will work well in extreme conditions.


This is the commercial standard that the Federal government set for penetrating fluids and is the base for all commercially designed penetrating oil products.

How to use penetrating oil

Every situation has its own application. As such, when focusing on rusted components, you need to bathe them in the penetrating fluid and let them sit for hours if not a day, and sometimes longer to allow the accumulated trust to be dissolved. You might need to reapply from time to time. In any event, the level of rust determines the amount of time to wait.

Non rusty components usually require less time, and varnish, glue, etc., require a penetrant that will dissolve the molecular bonds and turn them into slush.

Metal to metal forced surfaces such as aluminum will require a solid state lubricant, such as Teflon to provide a surface to a surface coating that eases the restrictions to torque.

How does penetrating oil work

Penetrating oil works in three steps, and this is for all types, whether they are cryo, solid state or plain old lubrication and rust removal.

The first thing you need to do is to determine the cause and then select the appropriate penetrating solution.
The second stage is to clean the area, including the surface entry point. This can mean a simple wipe, or a serious metal brushing to the use of an abrasion tool.

Once the entry point area is relatively clean, you need to either pour, inject or spray the penetrating oil, and do so slowly. Don’t try to speed up the process; you end up wasting the oil as it drips down the sides instead of seeping into the crack. Basically, you are going to either lightly coat the surfaces with a quick application, or totally bathe them with a long and tedious application.

For rusted surfaces, you will need to apply a lot, over a slow time, and then let the surfaces bathe in this liquid for any time starting from an hour for basic rust, to a week or more for totally rusted (ancient). For ancient rusted objects, apply a rust buster first, and only after applying a penetrating oil solution.

In some instances, you might need to make a couple of return applications, and always be patient.

After you have applied the solution, you can try to use a wrench or screwdriver to turn the components, if the component still doesn’t turn, wait, apply some more solvent and wait longer. If a standard issue doesn’t resolve itself within a day or two, you might need to consider using more torque rather than basic muscle power. Sometimes you need to wait a week or more, so patience is the only way to go here.

Also, do not use universal tools such as pliers of locking wrenches, these tend to damage the corners of the bolts, its best to use open end wrenches or even power tools for higher torque. When applying torque, make sure you don’t break the nut, if you do apply too much pressure you will end up with a broken part, and this leads you to perform “surgery” on the rest of the components.

If tools don’t work, even after a week considers trying a cryo option or, the opposite, using an oxy-acetylene torch to heat up the holding block (not the bolt). Cryo is applied to both surfaces and acts to contract the two creating a wider surface to the surface gap for the penetrant to work in better, while heat is applied only to the holding surface or block, making it expand slightly and allowing you to ease out the cooler bolt.

Combining heat and penetrating fluid can be problematic, since most penetrating fluids are volatile and will burn when exposed to flames, however, it is a tested and proven combination that works 99% of the time.

Now for an interesting approach, this one uses the heat to heat up the stuck bolt and the using wax (candle) placing it on the bolt, the wax liquefies and penetrates the surfaces, much as a penetrating solution does. You should heat the bolt up till it glows red. You then let the wax melt into the surface, let the bolt cool down and then apply torque to remove.

A similar performance is reached when using SiliKroil, their Kroil product has dimethyl silicones as part of its solution and works just like wax. Another Kano product is Penephite, that has graphite added, however after applying Penephite, you will want to clean out the surface to remove any remaining graphite.

Finally, we come to the cryo applications.

CRC and Bulls Eye have both got great cryo products that freezes the surfaces and is less destructive than heating with an oxyacetylene torch. The cryo principle is that you freeze the surfaces that come in contact with each other, causing them to contract. This creates a wider gap for the lubrication components as well as the solvents to do their work.

How long does it take for penetrating oil to work?

Depends on the application. For simple stuck joints, a couple of minutes, for rusted joints, maybe a few hours, for seriously rusted or ancient rust, weeks. If you don’t have the time to handle it, consider other alternatives to penetrating oil alone, as mentioned above, heat and cold. For seriously rusted components apply a rust buster first and then apply penetrating oil.

How to wash off penetrating the oil

After applying any penetrant, you need to clean the area and resurface it with proper lubricating oil, preferably one that acts as a good rust repellant (for lubricating and protecting, Vaseline is just as good in this case).
To clean, I suggest Medallion Premium Paint cleaner used in combination with a W-8006 Polishing Pad or stiff wire brush. Whatever you use, if it’s a ferrous surface that can rust, make sure it cleaned and dried and then apply grease or lubricating oil to protect the area from rusting over in the future.

How much rust can penetrate oil dissolve?

Essentially penetrating oil is not used for dissolving a lot of rust, these are not rusted buster products. These are usually used for simpler applications. That’s why a rust buster is the best application for seriously rusted components, before applying a penetrating oil.

Essentially most penetrating oils perform rudimentary rust busting, and they do so only to provide enough release so that basic torque will be enough to unscrew or release the components before applying a full cleaning process.
When comparing products, then WD-40 and JB-80 are lightweight petroleum products designed to wick into the threads and don’t actually “cut” rust. So these do not really rust removal products.

Liquid Wrench, Kroil, and PB-Blaster include rust-dissolving chemicals in their compositions and as such, uses these as secondary components to help the penetrant dissolved enough rust to make it “liquid” enough to turn the bolts with the aid of the lubricant.

Dissolving rust is more about time, there is a limited amount of solvent you can coat the surfaces with, and you need to “bathe” rusted components over time to totally dissolve the rust. As such, penetrating oils are not going to exhibit phenomenal rust cleaning attributes, for that you have rust cutter products.

To be honest, if you take automatic transmission fluid (ATF) and mix it 50:50 with acetone you get a great penetrating oil at a fraction of the price.

Product Comparisons

Machinist’s Workshop Magazine performed a study comparing various penetrating oils performance, and presented the results in their April 2007 issue. It turns out that the best solution is a homemade brew of 50:50 ATF and Acetone.

These are the test results (in brief)


No Application


PB Blaster  

Liquid Wrench  

Kano Kroil  

ATF-Acetone (50:50)

Force (Torque)

516 pounds

238 pounds

214 pounds

127 pounds

106 pounds

53 pounds

As you can see, after the home-brewed connection comes the best-bought solution that is Kano engineering’s Kroil, after that comes Liquid Wrench, PB Blaster, and finally the famous (or infamous) WD-40. The above test results are a major factor in all comparisons.

PB blaster vs. WD 40

WD-40 is a generic penetrating solution that actually works by dispersing water and applying a light coat of lubricating oil on the surface. As such, it’s not designed to remove rust, and will not perform as a rust remover when comparing it to the more powerful and toxic ingredients pf PB Blaster.

PB Blaster is made up from naphtha and petroleum oil, it is extremely viscous and can enter even the tightest of places, and you usually wait around 10 minutes as you would with WD 40.

WD 40 is also a very lightweight solution but comes with lighter ingredients too. The bottom line is that WD 40 is great to simply unstick stuck objects, while PB Blaster is for use on heavy duty applications that WD 40 is just not designed to provide.

This is like comparing a truck to a bike.

PB blaster vs. Liquid Wrench

This is a fight of the heavyweights, and based on tested results Liquid Wrench winds hands down. In fact, Liquid Wrench provides an extreme advantage of PB Blaster, and that is why it will perform much better on all applications.

The bottom line; while PB Blaster is a Truck, Liquid Wrench is a Turbo Charged Truck.

Kroil vs. PB blaster

There is no contest between the two, Kroil is the best penetrating oil in the world, proven in labs and proven in the field. Kroil will deliver faster, better and easier results than any other penetrating oil and apart from the damned ATF+ Acetone solution, is the best of the best. (Sounds like MIB 1)

The only difference between the two is that PB Blaster is much more available then Kroil, and as such, it has become a more widely used product. Who says that the best product is the most popular one? In this case it’s all about Logistics, something that turned Amazon into a giant.

Liquid wrench vs. WD 40

It’s time to take our poor light to weigh WD 40 and compare it to another heavyweight Liquid Wrench. Not fair, I will tweet it like Trump “Not Fair.”

WD 40 is a lightweight easy to use home used penetrant and not really designed to be a heavy duty industrial solution like Liquid Wrench. Guess what; there are more homes using WD 40 then there are companies using Liquid Wrench which is why WD 40 is so popular and a brand name. However, don t let that popularity fool you, the same way you would not use a home cooker in a restaurant, you won’t use WD 40 in a machine intensive situation.

Bottom line: WD 40 is popular because it’s used residentially, but it will never perform and is not designed to perform like Liquid Wrench. Two different markets, two different products.

3 in 1 oil vs. wd40

Now its time to look at the oldest brand against the most popular brand. Again not a contest, in this case, there is no contest, this is like comparing apples to oranges. 3 in 1 is an all-purpose lubricating oil that also works as a penetrant, while WD 40 is a simple lightweight unstick penetrant.

These are two different products, after all, 3 in 1 is great for bike chains, but would you use WD 40? Nope. So there you have it, buy 3 in 1 for general purpose lubrication and WD 40 for home-based unsticking use.

Tri-flow vs. WD 40

This is another unfair comparison, since Tri-Flow is an industrial lubricant more than a penetrating oil, and as such, is used to lubricate using micron-sized synthetic particles, PTFE and additives. As you can see, it’s so far from WD 40; this is not an apple and oranges case, this is an apple against loin steak comparison…how can you compare?

The bottom line, just as I wouldn’t use Tri-Flow on hinges, I wouldn’t use WD 40 on lubricating pistons.

CRC freeze off vs. PB blaster

Now, this is an interesting comparison since there is no lab proof to provide us with actual tested results. However, CRC freeze is the latest in cryotechnology and first of all contracts the metal surfaces, allowing the penetrating oils to enter and provide a much larger cavity to work in.

Based on customer reviews, as well as hands-on experience, CRC freeze works better only due to the nee freezing technology introduced. However, in terms of standard applications, where you wouldn’t apply a cryo system, PB will blast CRC out of the water.

Bottom line: each to its own, where a freeze is needed, then CRC is the king, where standard applications where freezing is not viable, PB is king. When comparing them, face to face in a similar application, CRC wins in price and performance.

Liquid wrench vs. Kroil

As mentioned above in the test results, Kroil is King. This is so true, however, when compared to Liquid Wrench, it’s a very close call, and to some negligible. So in fact, when you compare the difference in performance and the accessibility of both, I would have to say it’s a draw.

How To Choose A Penetrating Oil

There are slight differences in quality and price, but all of these products have been tested and found to work extremely well. At the end of this review article, I have posted two bonus articles, one on how to remove rusted bolts and the second is a review of natural household products that can act like penetrating oil when you don’t have access to penetrating oil.

The term oil in penetrating oil is a bit of misdirection since the percentage of oil in these substances differ widely from 10% to 70% dependent on the brand. Also, these substances come in a variety of applications, from true penetrating lubricants to penetrating rust removers and water displacement.

The chemicals used are also varied, where the most basic can be made of a home mixture including acetone and vegetable oil, others can be proprietary mixes of extremely long molecular chains.

In most cases, penetrating oil as they are grouped under, perform similar services including lubricating joints to remove sounds and maintain a frictionless condition, or remove rust to enable opening of rusty bolts, and there are also freezing solutions used to help snap stuck bolts. So, as you can see, there is a wide variety of applications under one name, sort of like saying Vehicle for cars, when it actually includes vans, trucks, and more.

What penetrating oils are doing for most is to penetrate between two metallic surfaces, spreading their liquid to provide some form of lubrication to enable one surface to rotate or remove against the other.

Tips on How to Remove Rusted Bolts

Anyone involved in the industry, or automation will come across a rusty bolt, a stuck part, a corroded piece of equipment. At home, we all have had to deal with rusty or squeaky hinges and small nuts and bolts that are stuck fast. Here is a small compendium of tips aimed to help make life a little easier when finding yourself in that annoying and frustrating situation.

Deciding if the bolt is Salvageable

All materials have a tensile strength, this means that they will withstand a certain amount of pressure before breaking or tearing. What you have to ascertain aforehand is where the bolt is rusted down to a thread, or if it is retained with a locking fastener, or whether the part it is attached to is sound.

If a locking element is found, you can ease that open by applying heat. The application of heat will expand the metal and allow you to release the bolt.

If the bolt is rusted, check to see to what extent. Clean it up with a wire brush and check the surrounding area. Apply some pressure, but not a lot, and see what budges. After this apply some penetration oil and try again. If the bolt is held fast, you need to decide whether it is worth saving or not.

In most cases, a rusted bolt has lost most of its tensile strength and breaking it off, or drilling it out might be a better solution.

Small bolts and screws are most often not worth fighting over, and it is quicker and less frustrating cutting them off.

Cleaning off the rust

If you have decided that the bolt is solid, and has good tensile strength, brush off the rust. After you have cleaned all the surfaces that were infected, brush off the base of the bolt (if it is visible). A clean base (end of the bolt) will reduce sticking when trying to unscrew it.

Choosing the right tools

Don’t blame the tool, it will only perform as well as the person wielding it. Make sure you choose the correct tools, this will reduce frustration and also focus the issue on the bolt and not the releasing process. In some instances, the head of a bolt can be worn away from rust, you might consider choosing a smaller gauge socket or wrench.

Remember your directions

Always remember that right is tight, the left is loose. You just need to remember the right is tight rhyme, the rest is simple. There are exceptions to the rule, so if you find a blot that doesn’t budge, check one that does and see if the right is tight rule fits it, by turning it left to release it.

What Are The Differences Between Penetrant Oils?

When you face certain large bolts or bolts and nuts that are in places too awkward to reach for cutting off, you will need to apply a penetrant oil and wait until it has seeped into the surface of the bolt. Don’t rely on one type of penetrant, keep at least two different types and alternate if the bolt proves to be extra stubborn.

If the sparse application of the penetrant doesn’t seem to work, then drown the bolt in penetrant oil. Don’t be sparse or stingy, apply it like a torrential reinforce and pour it all over the infected area. You might want to leave the bolt soaking a couple of hours, or even overnight.

Adding leverage

When some bolts prove to be extremely annoying, for instance, replacing a tire. Use leverage, take a strong pipe or other mechanical leverage options, and wear gloves. Apply pressure carefully, you don’t want to destroy the bolt while trying to release it. Try pumping the bolt as well as applying constant pressure. Pumping sometimes helps release incrementally.

A breaker bar or long-handled ratchet will give more leverage. Use a steady, even pressure paying close attention to the feel or each turn. If the tension suddenly becomes soft or rubbery, you are either breaking the bolt or stripping the threads. Wear padded mechanics gloves to reduce skinned knuckles and the number of quarters put in the swearing jar.

Heating and Firing

Some nuts can be released when eating is applied, causing the area around the bolt to expand. However, don’t use this in a confined area, and beware, penetrant oils are combustible. You also have to take care that no plastic or rubber parts are in the direct heating zone. A focused oxyacetylene torch is best when applying heat around a bolted area.

Molted paraffin

Some rusty iron parts can be released by heating the surrounding area and then melting a candle over the area, the paraffin wax acts as a great releasing mechanism. This is a good solution for threads as paraffin finds its way all along a threaded surface.

Breaking the Bolt

OK, you have tried everything, and nothing goes, there are two options, give up and get a new whatever, or break the blot with a pneumatic drill or strong hammer. If possible even grind or saw the head off. Then drill into the body of the bolt and removing it by eating it from the inside out.

Natural alternatives to penetrating liquids

If you don’t have access to a penetrant, either because you are stuck in the middle of a desert or a mountain, or perhaps it’s the middle of the night, and you ran out of it. There are some possible solutions. A research study performed by Engineering students at Drexel University in Philadelphia found that a mixture of 12.5% acetone (nail varnish remover) and household vegetable oil, will provide the same if not better performance than WD-40. This little tip is very useful for solving some of life’s bigger mysteries such as a squeaky door at home.


There are many different formulations under one heading, and as such, you need to consider what you need the penetrating oil for. In most cases, and in many garages and industries you will find an assortment of products lined up next to each other, where each one has a specific focus and is used based on that focus of the performance.

This means you would have Kroil, WD 40 and CRC Freeze on the same shelf, using each one for a specific range of applications. If you are in the food business, you would have food grade oils such as CRC.

This is why this list of 12 of the best penetrating oils is only the tip of the iceberg. To be exact, it’s not just about the penetrating oil but about the company. When you invest in any product, you need to buy from the best and most reliable sources, and this is the main factor behind this list — reliability.