Best Penetrating Oil

The Kano Kroil Penetrating Oil has the best active additives and EP pressure substances for the money. This best penetrating oil boasts of extra capacity and ruggedness to dissolve all unwanted molecules on metallic surfaces easily. The package it comes in is all loaded properly so that once you coat it on a surface, it gets clean. It’s ideal for loosening metal parts such as nuts, screws, bolts, and fasteners. It can penetrate between openings within minutes and improve mobility. All-in-all, the Kano Kroil the best lubricant that’s also a corrosion resistant fluid. If you want to stop rust and get rid of grease, this is what you need to buy. If you want a more naturally-occurring formula for removing grease, use this in combination with Babassu oil.

We found the SiliKroil Penetrating Solvent Aerosol to be the best penetrant oil for the money. It repels water, rust, and moisture effectively. And it has the best petroleum-based formula to loosen and unfreeze high-pressured parts. On the upside, it doesn’t leave anything behind, and breaks down oxidation and iron molecules to get rid of corrosion. When we talk about penetrants, the first thing we think of is ease of use. This oil doesn’t demand much from its user. You just have to spray it on the surface and let the EP additives to its job.

The PB Blaster Penetrating Catalyst is the cheapest penetrant oil that’s accurate and effective. It has a non-evaporating substance which helps it fight and resist rust better than other penetrants at this price. It also functions as a rust buster and not just a surface lubricant. The cleaning performance of this best penetrant oil is reliable. And compared to our previous picks, there is a good chance that you’ll keep relying on this for its incredible corrosion resistance and lubricating properties. We also found that taking this catalyst for camping is a good way to avoid accidents or car breakdowns.

A Little Background

Penetrating oil or fluid is a low adhesiveness oil that can be used on mechanical parts to removing rust. It’s a cleaner of nuts, bolts, and such parts and it’s a high-quality anti-corrosion lubricant. Once you apply a penetrating oil in between nuts or bolts, the fluid penetrates between these parts removing all rust and lubricating the mechanical parts. Similarly, with the way this fluid works you can also use it to remove adhesive stickers from surfaces, on metal-stringed instruments, and for general repair tasks. This can be for household, commercial, or gardening purposes.

The general purpose of the best penetrating oil is to reduce friction between mechanical parts. Now these mechanical parts happen to be as small as nuts and bolts. Most of you already know that oil, in general, can be used for many things. One of the oil’s top purposes is as fuel for transportation. Other uses include for cooking, manufacturing plastic and other synthetic products, and for lubricating surfaces such as metal parts for friction-less performance. For mechanical use, you do not need a CID parade to know what’s wrong with your equipment. All you need is a good eye and the best penetrating oil.

A penetrating oil acts as a good lubricant because it has extremely low viscosity, which means they aren’t thick. So, because of their thin texture, they can penetrate in-between mechanical parts effortlessly. It can also penetrate between cracks and minute spaces. Such a fluid contains anti-oxidants and other powerful reducing agents that help encompass, replace, and cleaner whichever surface it touches. And by doing so, there’s immediate rust and corrosion prevention while minimizing friction between the cracks, sealer spaces, or parts. So, all you had to do is pour or spray some of the best penetrating oil without applying extra force or pressure on the parts.  (1)

Such low-viscosity fluids were introduced with the WD-40 almost 70 years ago. It was composed using hydrocarbons for keeping rust and corrosion away from weaponry. These included stainless steel fuel tanks too. WD-40 is both a penetrating oil and a water-displacing spray. It was used for the maintenance of many commercial, industrial, and household items. Later, it was introduced amongst farmers for cleaning gardening tools and equipment. Contrary to modern low-viscosity fluids, WD-40 was manufactured non-volatile. But further processing of the fluid made it volatile for suiting domestic and industrial settings. The most common use for WD-40 was for removing rust and corrosion from nuts and bolts, loosening zippers and wicking away moisture from various surfaces. (2,3)

Types of Penetrating Oils

Based on its application, there are 3 types of low-viscosity fluids. Each type has its own unique effect for residential and industrial use.

Straight Oils

Straight oils are primarily manufactured and used by mechanics. They are non-dissolvable by nature and can be used for lubricating nuts and bolts and other mechanical parts in machines. Most straight oils are made up of petroleum-based liquids, vegetable oils, esters, or other high-pressure ingredients such as additives, phosphorous, or sulfur. They also feature a mineral base for longer-lasting performance. As for vegetable oils, make people use avocado or argan oil or castor oil for natural metallic lubrication. But this you should do after consulting a professional mechanic.

This kind of low-viscosity fluids contain more water which means they resist fire more effectively. These soluble oils should be used instead of high-inflammable oils in case where chances of ignition are higher than usual. This is the best application for straight or soluble oils on the market.

Water Soluble or Emulsion Oils

Unlike the previous type, water soluble fluids, such as General Finishes, contain very low water concentration. However, some also contain very high-water content. Such fluids can be used diluted along with other penetrants.

Synthetic or Semi-Synthetic Oils

A synthetic penetrating oil contain synthetic compounds such as silicone, esters, diesters, and other mixtures. Semi-synthetic oils contain a mixture of water and synthetic compounds. As a result, these types of penetrants have the highest rating of fire ignition resistance and are also the most expensive penetrants to buy.

How We Picked

High-quality penetrants are used to remove corrosion and rust from nuts, bolts, and such mechanical parts. What they’re not used for is as a substitute or alternative lubricant for heavy-duty industrial parts. The only functional use for the best penetrating oil is to loosen fasteners, nuts, bolts, wires, and the space between two seized mechanical parts.

Here’s what we looked at before choosing the best penetrants for our readers.


The most important thing or criteria we considered was the assessment of a penetrant’s features. We looked at the temperature restrictions of the penetrant which is commonly referred to as Flash Point. This term indicates the lowest temperature at which the fluid evaporates and creates a noticeable airborne ignition close to or on the liquid’s surface. Studies suggest that most penetrating oils can get volatile if the Flash Point is low.

If you want a penetrant for industrial applications that require high temperature, this is mostly true for electrical parts, buying a penetrant with a high temperature Flash Point is necessary. Out of all the main types of penetrants, straight oil is more inflammable. While the remaining two types are not. That’s because the latter feature much low Flash Point markings. The only important measure you need to move forward with are the operating temperature settings. They break down all you need to know about the temperature when the fluid has an effect.


The second important thing you need to see is the Dielectric strength of the penetrating oi. This is the maximum amount of voltage a penetrating oil can endure before a breakdown occurs. The highest point of dielectric strength needed from penetrants is for electrical appliances or equipment that is used for dealing with high-load electrical appliances.

Water Displacement

There are two types of water displacement features and you have to choose either one based on what you’re planning to use a penetrant for. The first kind displaces water content from a surface. This is done after wetting the surface with the fluid. The second kind has extremely low surface strength and interfacial tension, which means it moves water underneath moisture on the surface.


Do you need low amounts of foam or no foam at all? You get all kinds of non-foaming and foaming penetrants. Non-foaming penetrants contain additives that reduces the amount of air bubbles or leaks from the fluid. Such leaks are responsible for creating foam as it allows proper circulation of thermal oil, hydraulic oil, and grinding coolant. If you want a penetrant with fewer cooling abilities, opt for a foaming kind.

Safety Standards

The last thing is looking for the safest and most effective standards. The 2 primary standards for the best penetrating oil are MIL-PRF-24548 and A-A-50493. The former deals with penetrants for loosening frozen fasteners, metallic parts, corrosion, and for direct application. The latter is also responsible for penetrants manufactured to loosen corroded metallic parts, frozen fasteners, etc. But unlike MIL-PRF-24548, A-A-50493 is responsible for establishing certain performance and design requirements based on government standards for such penetrants.

Our Best Pick

After putting in hours of research, the Kano Kroil Penetrating Oil is worth paying for. It’s lightweight, reliable, and easy to use. So, right now, this best penetrating oil is the highest ranking choice for most people. With active ingredients to reduce surface tension and boost the fluid’s penetration into surfaces, the Kano Kroil is a tough choice. It helps with lubrication, displacing water molecules, and preventing rust formation. Not only that its effectiveness is reliable, Kano Kroil’s incredibly convenient to use. We found that it works efficiently to unfreeze surfaces with high tension; all thanks to its advanced and unique specializing process. The Kano Kroil adopts a process gets absorbed within seconds into threads and openings. Even if they are narrower than half an inch.

The Kano Kroil can be used to remove dried grease, gum, and rust from metallic parts. It’s also safe and effective to use on industrial, mechanical, and weapon parts. If you want something that penetrates and lubricates in mere minutes, the Kano Kroil product works very well.

Flaws but not dealbreakers

It’s because this best penetrant is so powerful and effective that leaving it on the surface would lead to deterioration of the treated surface. The Kana Kroil is designed to loosen frozen fasteners, nuts, or bolts in minutes which means it’s extremely good at dissolving corrosion and rust.

Hence, if you do not wipe the surface down after using this penetrant, some sensitive parts of the surface might get loosened and fall off. And so, cleaning the penetrant is necessary and might be a bit tedious for some of you.

Our Best Step-Up Pick

The SiliKroil Penetrating Solvent Aerosol is a petroleum-based lubricant/corrosion repellent. It’s also a reliable surface water repellent which fits into extremely narrow spaces. It’s the best available alternative to WD-40 because it’s much faster and accurately efficient than other products. This best penetrant is also good at lubricating for long-term use. It breaks down molecules of iron oxide to dissolve rust and prevent it from contaminating the metal parts. The first step to getting rid of rust and corrosion is to fight oxidation. This oil resists wetting which contributes to oxidation and then loosens both stubborn and semi-transparent stain efficiently. This specialized process is extremely effective at getting rid of any kind of unwanted particles on the surface, including moisture, humidity, and dust. Now, you will be able to take all important metal parts, clean them with this best penetrant oil, and watch every part run as smoothly as ever!

As with electrical parts, they come under incredible pressure from heating and cooling in a cycle. And so this best Sili Kroil penetrant is a must have for loosening or unfreezing such connections. All you have to do is spray the fluid on the metallic parts and leave it overnight. This stuff works overnight to loosen parts that are tightly wound.

Our Best Budget Pick

The PB Blaster Penetrating Catalyst is probably the best brand to buy from. It’s effective, lightweight, and durable. It has been used for numerous automotive, industrial, marine, plumbing, and commercial purposes. The PB Blaster can prevent rust and lubricate a wide range of surfaces and parts including pipe threads, fasteners, frozen joints, and squeaky metallic parts. The PB Blaster is not just a penetrant oil, but it’s also the ideal rust buster for most people right now. The non-evaporating substance present in this oil makes it the exceptional rust buster at a good price. This means the fluid doesn’t interfere with the metallic parts unless it’s supposed to prevent rust from settling on them. This best PB Blaster even lubricates so that the parts run smoothly and without scrubbing against the other.

This best penetrating oil has its general use amongst resisting rust and corrosion on nuts and bolts. And compared to WD-40 which is a lubricant per se, this best penetrant oil is the ideal rust penetrant. For better results, you can add ATF-acetone mix or automatic transmission fluid with this catalyst. The acetone combination sting and does its job of lubricating and reducing rust effectively. Lastly, this best budget pick is a real time-saver. You just have to wait for a few minutes for it unscrew and unfreeze parts with ease.

Our Best Fastest-Acting Penetrant

The Liquid Wrench L106 is a safe and effective penetrant to use. It comes with an anti-VOC formula, which means it doesn’t have a pungent odor and is safe to use for multiple projects. This is the ideal multipurpose penetrant oil on the market. We like it because it loosens screws, locks, bolts, and nuts easily. The Liquid Wrench even contains activated aerosol which means it have the fastest acting solvent without the fuss. You can keep this best pick if you want fast performance and effectiveness – all at a good price. Penetrant oils such as the Liquid Wrench are known to last twice as long and be twice as effective as most.

Our Best Penetrant for Mechanic Use

The Castle Thrust Penetrating Oil is a good choice for automotive and mechanical use. If you’re willing to invest in a penetrant oil that has a good thrust and lubricating feature, this is what you need. It helps eliminates any kind of squeaks, noise, or scrubbing sounds from parts. If you want to service a mechanical part such as a nut, bolt, screw, fastener, spark plug, lock, etc. this one gets the job done. Buy this best penetrant oil solely when you want high-grade affinity and an ion-activated fluid formula for long-term use. The Castle Thrust is known for its fast-acting and super-effective lubricants. It even resists higher temperatures and still provides excellent lubrication for the price.

Our Best Penetrant with Straw

The Pipe Break Penetrating Oil is an easy to use, effective, and anti-corrosion penetrant oil. It’s easy to use because it comes with a straw so you can squeeze it in tight corners. More importantly, your hands stay clear of the fluid which makes apply it on surface much less complicated and messy. It’s effect because it contains powerful activated formula for loosening screws and nuts and bolts within minutes. And anti-corrosion because it breaks down oxidizes molecules to resist and keep the surface from appealing to rust on a consistent basis. Until you keep applying this best penetrant oil, it will keep protecting your equipment from corrosion and moisture build-up.

Our Best All-In-One Penetrant

The Gasolia Free All Rust Aerosol is just like our favorite budget pick – it’s a dedicated rust buster that’s also an effective lubricant. This best penetrant in particular has everything a standard lubricant/anti-corrosion repellent needs to remain efficient. It’s suitable for unfreezing and loosening grease, graphite deposits, tar, and white and red lead from metallic parts. Similarly, it will free pipe threads, joints, locks, machine screws, rusted muffler parts, and much more. It’s the best all-in-one penetrant for consistent use. And it’s safer too because it contains no VOC or silicones. Which makes it good for paints and household environments.  

Our Best Penetrant for General Use

As compared to a more faster-acting fluid, such as the Liquid Wrench, the 3-IN-ONE 10038 Multi-Purpose Oil is a good standard staple for most people right now. It may have its exceptions, but it’s a general-use only penetrant on the market. That said, it comes with a durable drip applicator which helps you sprays it more accurately on the parts. If you’re looking to carry out some servicing or maintenance of squeaky parts, this is what you need to buy. It has everything one needs for lubricating and make sure that rust and corrosion are at bay. Lastly, this is a squeeze bottle which means it’s easier to store and carry around for multiple situations.

Our Best Penetrant for Metal Parts

The Kano Aerokroil Penetrating Oil is a dual functioning penetrant oil. It loosens stuck nuts and bolts while decreasing the surface tension of metallic parts. The latter is important because it increases the shelf life of most metallic parts by balancing the temperatures of the surface. This also has an impact on resisting rust, grease, gum, tar, and moisture. It contains high-quality solvents that dissolve rust and lubricate the surface. You can use the Aerokroil as many times as you like and it still won’t damage the metal. This Kano Aerokroil Penetrating Oil is a best rust penetrating oil that’s good for its quick and effective use.

Our Best Eco-Friendly Penetrant

Our last pick is the Liquid Wrench L103 which is a reliable and effective low-odor and non-VOC penetrant oil. It performs well against rust, corrosion, gum oil, and grease. And since it contains no VOC compounds, it’s one of the best penetrant oils to use for homes. Everyone wants an environmentally-friendly product for cleaning wood, metal, and plastic surfaces. For example, AFM Safecoat is the leading provider for eco-friendly and sustainable paints, oil-based stains removers, and sealers.

You can use it for nuts, bolts, hinges, pipe threads, locks, and other fittings. It as persistent and efficient as you want it to be. And you won’t have problems applying it on smaller parts because it contains no pungent smell. All these features make this best penetrant easy to use and lighter than most brands. Such type of an eco-friendly penetrant can also be used with ATF acetone and vegetable oil such as olive oil for better results.

The Competition

Do you need more than one? The entire point of using a penetrating oil is to make sure it’s the right type for the surface you’re using. Sometimes, one type of penetrating oil is not the best universal choice for all surfaces. Hence, check the oil before you buy it for multipurpose use. You can buy more than penetrant for loosening screws, nuts, bolts and for resisting corrosion. In fact, you can buy one to lubricate, one to decrease surface tension, and the other for anti-corrosion performance. It’s completely safe to use more than one penetrating oil for maintenance and servicing. We also have many dual function penetrating oils such as the Kano Aerokroil penetrating oil. That said, if you’re still skeptical about using penetrants for long-term use, you can try alternatives such as acetone and vegetable oil and automatic transmission fluid along with a penetrating catalyst. It might be the cheapest way to use penetrants with acetone and vegetable oil or another other compatible lubricant, but it may as well be the most effective too! The choice is yours.

Frequently Asked Questions

  1. What are penetrants used for?
  2.  Penetrating oils, such as Aero Kroil, are good for loosening all kinds of corrosion, rust, and frozen fasteners that have been subjected to dirt and years of conduct. A penetrant oil has comparatively low viscosity which gives it an edge over all other lubricants to penetrate into the pores of numerous surfaces. As a result, you are no longer have to tear your hair out when it comes to hiring professionals to get the job done which you can do so easily. That said, the most common way to use a penetrate is to combine it with a lubricant and/or a solvent for reduce the viscosity and increase the surface thinness of the fluid for certain applications.

Here are some of the common uses of the best penetrating oil on the market:

Cleaning Agent

There are all types of cleaning agents for metal, wood, and other materials. Penetrant works for metal parts, however if you want something for wood, look for Restore-A-Deck cleaner or Behr Deckover for cleaning semi-transparent deck stains or any other prominent deck stain that’s hard to remove. Another significant or wood polisher is Pallmann Magic Oil which works for removing wood stain and giving the surface a refreshed appearance.

A penetrate is used as a cleaning agent to get rid of any stickiness, dirt, rust, tars, corrosion, and grease. Most times with corroded knobs and pulls or over-used mechanical parts, the surface is highly prone to developing a film of gooey adhesive which can only be removed and prevented with the help of penetrant oil. Just as how a concrete sealer protects the surface from damage and corrosion, the oil acts as a quintessential solvent cleaner and dissolves the impurities from the surface. Once this is done, you can wipe the area clean with a microfiber cloth or a light abrasive to make it glossy. A tack cloth can also be used to wipe a surface clean of the oil mixtures.


Lubrication is the base function of all penetrant oils. It is used for reducing friction between industrial and mechanical parts, but since the best penetrating oils are volatile, they leave behind a thin surface. Unlike anti-seize compound products, these types of penetrants can easily be contaminated and have a high evaporating ability. Hence, for long-term lubrication using a penetrant oil, adding additives to increase the shelf-life of the fluid is important. One such example for excellent lubrication would be the Kano Kroil penetrating oil or the Liquid Wrench penetrating oil.

However, it must be said that using penetrating oils as a replacement for high-grade industry lubricants is strictly prohibited. This is because many mechanical parts require high-grade lubrication with a minimal evaporation rate. Another popular lubricating agent are fatty acids because they help reduce friction and break down molecules to prevent any kind of mechanical restriction in movement. (4)

Corrosion Prevention

Corrosion prevention also includes resistance and reduction of corrosion from all kinds of surfaces. Corrosion, research suggests, is an electrochemical reaction. It forms when acidic substances such as water come in close contact with iron or steel surfaces causing rust to form. This can be chemical or atmospheric corrosion. The best way a penetrant oil fights against the corrosion is by stopping oxidation of water and replacing it with moisture. This is possible with water displacing properties of a penetrant oil. That said, unlike penetrating fluids, a standard corrosion resistant lubricant will leave behind a durable and non-conductive film. This acts as a corrosion preventer which creates a tough barrier between the atmosphere the surface of the mechanical parts. So, you can say that the functionality of a penetrant is different than most lubricants or cleaners in many ways. (5,6)

  1. What do penetrants contain?
  2. The best penetrant oil contains a mixture of extra pressure additives, corrosion preventers, and micro dispersants. Let’s study each one of them to better interpret the composition of the best penetrating oil.

Corrosion Preventers

A corrosion preventer or a corrosion inhibitor is an additive used to reduce, prevent, and control the amount of corrosion on a surface. With the required quantity of corrosion inhibitor fluid in the penetrant, low and high degree of corrosion contamination can be prevented. However, corrosion inhibitors are extremely strong and can be used to achieve desired corrosion resistance even when used in lower concentrations. The most common corrosion fluids use electrostatic force to absorb the rust and corrosion on the treated surface. Or they can also react with the rust particles on a passivation layer to create a friction between the atmosphere and the treated surface.

Extra Pressure Additives

Extra pressure additives are polar molecules that are responsible for reducing the tension between metal surfaces. An EP additive looks like a minute body or a molecule having a head and a tail. The head of the molecule to drawn to the metal surface and the tail contains the primary carrier of the penetrant oil. To reduce friction between metal surfaces that have been exposed to high pressure and atmospheric changes, the carrier reduces the tension created by such high-powered mechanism. It also helps reduce constant rubbing and makes the metal-to-metal process much smoother. Based on research, there are two main types of EP additives to look for in a penetrant oil:

  1. A temperature-driven additive reacts with metal surfaces especially when the temperature is higher than usual. This can be best used for high-pressure mechanical parts.
  2. A non-temperature-driven additive is activated regardless of the low or high heat properties of the surface. It works by dispersing salt molecule with sulfonate. This creates a durable barrier between the surfaces. The only difference here is that this type of additive doesn’t need higher temperatures to do its job. (7)

Micro Dispersant

A micro dispersant is what evaporates after coating a treated surface with a penetrant. They are primarily used to improve mobility of metal surfaces. Also, with the help of micro dispersants, other additives are absorbed faster and more effectively for better results. Common micro dispersants are graphite, boron, molybdenum disulphide, and boron nitride. (8)


  1. Is there an alternative to using the best penetrating oils?
  2. There are many other ways to reduce rust, clean, and lubricate metallic parts other than using a penetrant oil. You can substitute a penetrant with vegetable oil or acetone or automatic transmission fluid to have similar effects. However, studies recommend that using penetrant oil along with acetone, transmission fluid or vegetable oil, in an efficient manner, can have better results.

Automatic Transmission Fluid or ATF is best used with acetone for penetrating mechanical parts such as nuts, fasteners, and bolts. Many mechanics and professionals use this mixture to remove rust and improve mobility in frozen fasteners.

Vegetable oil can also be combined with acetone. It’s probably the most inexpensive way to lubricate and improve the condition of metal surfaces. Acetone has its application for beauty products such as nail paint remover and for commercial uses such as paint thinner. Hence, it’s an active ingredient, like the ones present in Liquid Wrench penetrating oil that can be effective at removing rust from nuts and bolts when combined with vegetable oil such as avocado oil or acetone.

There are many alternatives to using such penetrants, such as avocado oil, linseed oil, olive oil, coconut oil, etc. But it’s important to remember that not all metallic parts get along with such alternatives.

Making your own homemade penetrant

All you need to make your own penetrant is acetone and automatic transmission fluid. A 50/50 mixture of both these ingredients is good enough. Plus, if you add a good industry-grade penetrate, the lubricant/penetrant could take effect faster and more effectively.

Note: An ATF-acetone mix is more flammable than commercial products, so please make sure you use it only outdoor use (for electric water heaters) and away from sensitive equipments or flames. They’re comparatively slower-acting than commercial products, but they do an effective job!   

  1. What is the difference between a penetrating oil and a rust buster?
  2. A penetrating oil is a lightweight lubricant with corrosion resistant properties. It can be used for mild to moderate-level rust contaminations on metallic surfaces. On the other hand, a rust buster is specifically manufactured to fight rust and for long-term corrosion resistance. Products such as WD-40 and JB-80 are lightweight penetrants designed to lubricate, improve mobility, and prevent rust and corrosion. However, they won’t do a heavy-duty job at preventing corrosion as a rust buster.

Similarly, certain kinds of penetrants come with water dispersing qualities that help reduce water content from surfaces and mechanical components. This reduces the penetrant’s ability to resist corrosion to a higher degree. Products such as Liquid Wrench, Kroil, PB-Blaster have rust-dissolving properties that are manufactured to dissolve rust while providing lubrication. This would be mean long-term protection against corrosion and better and upgraded mobility between two metallic surfaces.

A rust buster, on the other hand, requires more time and effort. What this means is that rusted bolts and nuts that are extremely contaminated with rust and corrosion need to be soaked for a few days in a rust buster fluid. The results are often highly effective and incomparable after.

Wrapping it Up

The Kano Kroil Penetrating Oil is our consistent and top-performing penetrant on the market. What makes this best penetrant oil a hard-to-beat choice than most other brands? It has a fast-acting and a strong activated solution to reduce surface tension, lubricate, and prevent corrosion. The Kano Kroil penetrating oil has the kind of ingredients most mechanics and professional need in a penetrant fluid. We consider the Kano Kroil to be the ideal go-to pick for anyone looking for a backup tool for taking care of all kinds of mechanical, industrial, or electrical parts. You can also use it with acetone or other compatible oil-based products for more effective results.

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