10 Best Penetrating Oils – Reviews and Buying Guide

Best Penetrating Oil

Penetrating oil is oftentimes a lifesaver to have in your car because it makes the loosening of bolts, hinges, and locks a piece of cake.

For those times that you need to get two pieces of metal away from themselves, but they don't seem to budge, no matter how hard you try, nothing works as good as penetrating oil.

There are different types of penetrating oil, manufactured and sold by different companies, and this leaves a lot of products to choose from.

With this review, you get a list of the top penetrating oils on the market, plus an in-depth buying guide to help you make the right choice.


Product Name



Current Price

Kano Aerokroil Aerosol Penetrating Oil

1. Kano Aerokroil Aerosol Penetrating Oil

10.0 oz


Kano Kroil 8-Oz Penetrating Oil

2. Kano Kroil 8-Oz Penetrating Oil

8.0 oz


Kano Sili Kroil Penetrating Oil

3. Kano Sili Kroil Penetrating Oil

16.5 oz


Castle Thrust 15.75-Oz Penetrating Oil

4. Castle Thrust 15.75-Oz Penetrating Oil

15.7 oz


CRC Knock'Er Loose Petroleum Based Penetrating Oil

5. CRC Knock'Er Loose Petroleum Based Penetrating Oil

11.5 oz


WD-40 Multi-Purpose 2-Way Spray Penetrating Oil

6. WD-40 Multi-Purpose 2-Way Spray Penetrating Oil

8.0 oz


B'laster 8-PB Penetrating Oil

7. B'laster 8-PB Penetrating Oil

7.0 oz


B'laster 16-Pb Penetrating Oil

8. B'laster 16-Pb Penetrating Oil

11.0 oz


Loctite 12-Oz Penetrating Oil

9. Loctite 12-Oz Penetrating Oil

12.0 oz


3-In-One 8-Oz Multi-Purpose Penetrating Oil

10. 3-In-One 8-Oz Multi-Purpose Penetrating Oil

8.0 oz


Editor's Rating: 4.7 out of 5 stars (4.7 / 5)

Kano Aerokroil Aerosol Penetrating Oil

In the world of penetrating oils, Kano's Kroil oil stands out from the rest. The company owes this success to their laboratory breakthrough, which created the Kroil oil that can creep into a millionth of an inch space.

This offer is for the Aerokroil, which is the Kroil oil in aerosol version. It's perfect for certain applications since all you have to do is point and spray, and when the rusty metal in deep inside a confined space, you can easily attach the included straw for correct application.

Simply spray it and wait a few minutes for it to loosen frozen metal joints, dissolve dried grease, oil, and gum. It will also displace water and it offers some level of lubrication as well, all without attacking the surrounding metal.

The Kroil penetrating oil brand is a widely trusted brand far and wide, and it's known as a penetrating oil with no equal. The only issue here is that it has a petroleum base, which means it's not ideal for certain applications.


  • Kroil oil creeps everywhere including into a millionth of an inch
  • Dissolves everything without attacking the metal
  • Loosens frozen metal joints very quickly
  • Comes in an aerosol container and includes a straw applicator


  • Contains petroleum, so is probably not for all kinds of jobs

Editor's Rating: 4.8 out of 5 stars (4.8 / 5)

Kano Kroil 8-Oz Penetrating Oil

This is the original Kroil oil that got presented in an aerosol form in the earlier product. Kano's Kroil oil is well-known for its ability to loosen the toughest stuck-together metal parts.

Based on its very low viscosity, this oil is known to easily penetrate spaces as small as a millionth of an inch, making it the go-to oil for any rusty metal issues.

Unlike the earlier product, this one comes in a can with a spout for precise application. You can also choose to improve your precision by turning the oil into a bottle with a needle tip.

It's important to note that having such a low viscosity also means less lubricity for Kroil oil. It does lubricate though, but it's much more penetrating than lubricating.


  • The original Kroil penetrating oil for direct application
  • Features a spout for precise application of the oil
  • Practically has no expiry date
  • High-quality oil offered at an attractive price


  • Contains petroleum oil, so it may have harmful effects on some materials

Editor's Rating: 4.6 out of 5 stars (4.6 / 5)

Kano Sili Kroil Penetrating Oil

The original Kano Kroil is a good penetrating oil with a very low viscosity and good penetrating power, but this is often not enough because some situations will also need a good level of lubrication to get things done.

What Kano did, was to add dimethyl-silicones to the mix, which increases its lubricating power and makes it easier to loosen old stiff joints that have already been broken apart by the penetrating oil.

The lubrication is also long-term, making this Kano Sili Oil very suitable for particular situations. In addition to lubrication, the silicon helps to keep away moisture, which in turn helps to prevent rust.

What you get here is an oil that penetrates down to one-millionth of an inch and additionally offers a lasting and good amount of lubrication.


  • Offers Kroil's high-quality penetration and loosening
  • Includes silicon enhancement for more and longer lubrication
  • Repels water very well and keeps the area free from moisture
  • Offered in a 16-oz aerosol can for easier and longer application


  • Kroil oil is petroleum-based and so, not fit for all materials

Editor's Rating: 4.6 out of 5 stars (4.6 / 5)

Castle Thrust 15.75-Oz Penetrating Oil

Castle offers the Castle Thrust as a penetrating oil with a range of features to improve its penetration efficiency and other factors.

The first feature is Thrust, which is an ion-activated feature that uses the oil's affinity for metal to make it penetrate deeper and faster than with other penetrating oils, cutting down on the time needed to loosen any piece of metal.

Another feature is its foaming nature, which helps to keep the low viscosity oil focused on a particular area. Normal penetrating oil will run off and spread out immediately, but Castle Thrust's foam helps it to stay focused and slowly seep into the metal.

It's also highly temperature-resistant, but it's still flammable and will release hazardous flames when it burns. Else, just spray it on the affected metal and wait just 3 minutes and it'll complete its magic.


  • Comes in an aerosol can for easy and fast spraying
  • Ideal for a range of applications
  • Ion-activated penetrating oil for faster and better results
  • Foams on contact to prevent oil runoffs
  • Can resist high temperatures


  • Petroleum-based oils
  • It's flammable and inhaling its fumes is hazardous

Editor's Rating: 4.4 out of 5 stars (4.4 / 5)

CRC Knock'Er Loose Petroleum Based Penetrating Oil

Here's another top-rated penetrating oil, designed for use in both loosening rusted metal parts and frozen ones. It uses a unique free-action system to crack rusted surfaces and then seeps deeper and faster than comparable oils.

It achieves this by immediately dropping the temperature of the area that it is in contact with, thereby cracking blockages and letting the penetrating oil seep through and do its job.

The Knock'Er Loose comes in an aerosol can that can get sprayed from all 360 degrees, including up and down. It is Volatile Organic Compounds (VOC) compliant and certified NSF-H2 for use in meat processing plants.

On the other hand, this is not the kind of penetrating oil you would use on hot areas, especially near your car's engine, because of its highly flammable nature.


  • Designed to loosen both rusted and frozen metal parts
  • Comes in an aerosol can for quick and easy application
  • Uses a unique freeze-shock action to penetrate deeper
  • Works on locks, hinges, nuts, bolts and lots more


  • It's a highly flammable solvent

Editor's Rating: 4.6 out of 5 stars (4.6 / 5)

WD-40 Multi-Purpose 2-Way Spray Penetrating Oil

WD-40 is a well-known brand when it comes to lubricants and penetrating oils. In fact, lots of people refer to it as the can with thousands of uses because of its wide range of potential applications.

First invented by the military for cleaning up missile parts, WD-40 today is mostly used to penetrate and free stuck parts, lubricate moving parts, protect metal from corrosion, and displace moisture.

This aerosol can's volume is 8-oz and it comes with a special spray head that offers two application methods. The head includes a straw that can get used for streaming the solvent, making for precise application.

You can also decide to turn down the straw and then spray the solvent out of the can. WD-40 will remove grease, gum, gunk, grime, super glue, and lots more.


  • Comes in an easy to use 2-way spray can
  • Spray head includes a straw for precise applications
  • It penetrates, lubricates, displaces moisture & halts corrosion
  • Well known and trusted brand


  • Its lubricating effect doesn't last long

Editor's Rating: 4.4 out of 5 stars (4.4 / 5)

B'laster 8-PB Penetrating Oil

If you're looking for a penetrating oil that's as cheap as possible, this 8-PB from B'laster is something you should take a closer look at.

It's a true penetrant, which saves you time and money by creeping quickly and deeply into all spaces. The B'laster penetrating oil easily breaks up rust and frozen bolts, allowing you to carry on with your job.

It also includes a non-evaporating lubricant to help in loosening bolts and other moving parts, plus it protects against further rust and corrosion.

The B'laster 8-PB penetrating oil is ideal for use on your car and all other machine or industrial applications. You can get it in either this 7-oz can, in an 11-oz can, or in a large 5-gallon pail.


  • Creeps into the tightest of spaces to loosen everything
  • Provides lubrication as well for moving parts
  • Works very quickly and effectively
  • Additionally, provides corrosion resistance to metals
  • Offered at a very low price


  • Has a low flash point of just 150 degrees Fahrenheit

Editor's Rating: 4.5 out of 5 stars (4.5 / 5)

B'laster 16-Pb Penetrating Oil

This penetrating oil is the same as the one above, but it just comes in a larger can for longer use. You get an 11-oz penetrant made from a concentrated copolymer.

Designed mostly for penetration and loosening rusted or frozen metal parts, it does offer a level of lubrication as well, but this is low and short-term compared to the other offers in this penetrating oil review.

The B'laster brand is very popular and has been a top-selling penetrant since the 1950s. It will easily break rust bonds and frozen metal parts and protect them from further corrosion as well.

Any of these two B'laster offers is great to try, especially when you consider their low prices. The difference between them is just the size of their cans and the volume of the product inside.


  • 11-oz container is larger than the earlier B'laster
  • Breaks rusted and frozen metals free
  • Good for use on cars, boats, plumbing, e.t.c.
  • Features anti-corrosion properties


  • Flashpoint is 150 degrees Fahrenheit
  • Its lubricity is not much

Editor's Rating: 5 out of 5 stars (5 / 5)

Loctite 12-Oz Penetrating Oil

Loctite is a lesser-known penetrating oil brand, but one which makes an impressive range of cleaning and lubrication products.

This offer is for a 12-oz aerosol can with Loctite penetrating oil, designed to quickly cut through rust and dirt to loosen any bolt, hinge, or pipe. It also protects against corrosion, although its lubricating properties are not much.

In addition to ordinary rust, it will free frozen items like pipes, valves, and bearings, as well as sticky ones. It comes in a large, 12-oz container and includes no ozone-depleting compounds.

Read More: 10 Best Wheel Bearing Greases

On the flip side, it's a much less known penetrating oil than most others on this list, its price is not attractive, and its heat-resistance is equally unimpressive.


  • Seeps very quickly into the tightest spaces
  • Includes anti-corrosion properties to fight off the rust
  • Versatile oil is ideal for a range of applications
  • Completely free from ozone-depleting compounds


  • Extremely flammable

Editor's Rating: 4.6 out of 5 stars (4.6 / 5)

3-In-One 8-Oz Multi-Purpose Penetrating Oil

The 3-In-One multi-purpose oil is the oldest penetrating oil on this list, having been available for over 100 years. It offers the 3 jobs of penetration, lubrication, and protection of tools and other items.

You too can find it useful for your car or rusty tool, especially its long drip spout, which makes it possible to lubricate hard to reach areas that might prove difficult possible otherwise.

Its lubrication is long-lasting, unlike most other penetrating oils on this list and coming in a squeeze bottle allows you to apply the right amount of oil each time.

The 2-In-One is also the cheapest offer in this review and this makes it the number #1 choice for those on a budget.


  • Quick-penetrating oil gets the job done very fast
  • Also works well as a great lubricant
  • Comes in a squeeze bottle to control applications
  • Long drip spout provides access to hidden spaces
  • Offered at a low and attractive price


  • The oil cannot get sprayed

How to Buy the Best Penetrating Oils

How to Buy the Best Penetrating Oil

Although any penetrating oil might just seem like penetrating oil at first, there are small differences between the different types available, and these differences also make each one better suited for different tasks.

Following is a closer look at the different important properties of penetrating oils. You have to know and look out for them when reaching your decision because knowing them will help you to choose better.

#1. Your Purpose

This is the first consideration you should make because it'll help you to decide to a great extent, the right kind of penetrating oil you should buy.

In addition to loosening two metal parts, penetrating oils can also function as short-term lubricants, as well as cleaning agents, and in preventing any further corrosion.

It matters a lot if you're using the oil on hot metal because some are less fire-resistant than others. The type of surrounding materials also matters because some materials can get damaged from certain types of penetrating oils. There are three major types of penetrating oils.

#2. The Types of Penetrating Oil

There are three major types of penetrating oil and they each have their advantages and disadvantages over one another. They are straight, emulsion, and synthetic penetrating oils. Following is a closer look at each type.

  • Straight Oil. The name straight oil comes from the fact that this type of penetrating oil gets made from petroleum oils and base minerals and they're meant to get used as they are, without diluting. Straight penetrating oils are mainly used for machine parts and usually contain polar lubricants like vegetable oils, esters and fats, and additives like sulfur, chlorine, or phosphorus sometimes.
  • Water Soluble or Emulsion Penetrating Oil. The second type of penetrating oil generally features fluids that have a high-water content and they are usually diluted to a great extent as well. These oils generally have concentration levels below 10% and are mostly used on materials that may get damaged when any of the other types of penetrating oil gets used.
  • Synthetic & Semi-Synthetic Penetrating Oils. This third type refers to penetrating oils based on synthetic compounds like silicone, esters, diesters, polyglycol, and different mixtures of synthetic fluids with water. The major advantage of synthetic penetrating oils over the rest is their high level of fire resistance. On the other hand, they also tend to cost more.

#3. Ease of Use

When deciding on any particular brand of penetrating oil, also make sure that it's easy to use for the purpose you bought it for. This simply means buying the right product that works straight out of its package.

#4. Viscosity & Lubricity

Viscosity is a measure of the internal friction in fluids, and it goes from thick to thin. Highly viscous fluids are thick and can't penetrate anything, while low-viscosity fluids are very thin.

Penetrating oils have a low internal friction or viscosity and are more penetrating as a result. Additionally, the lower a penetrating oil's viscosity, the more penetrating it is.

In addition to penetrating tight crevices and loosening rusty objects, a good penetrating oil should also offer some sort of lubrication to help nuts loosen from bolts or make hinges swing smoother.

#5. Temperature Tolerance

Different materials have different temperature and fire tolerances and this is often an issue with penetrating oils because they could get used on hot items.

If you think you might have to loosen hot or fiery items, then investing in a synthetic or semi-synthetic penetrating oil would be a great idea because of their high level of fire resistance.

#6. Eco-friendliness

If you're the Eco-friendly type or if you have to use penetrating oil in an environmentally sensitive area, then choosing an Eco-friendly penetrating oil will be the right thing to do.

Environmentally friendly lubricants are available in all three types of penetrating oil. They offer you a reduced impact on the environment while maintaining high lubricant performance.

#7. Price

The issue of price is one that you'll have to deal with by yourself. This is because it's only you who knows how much you're willing to spend on a penetrating oil.

Manufacturers who use the best ingredients in making their products, usually offer them at a higher price than the others, but this doesn't always mean that they're better.

In this case, it's left for you to know how much you're comfortable with spending and then look for a penetrating oil package in that price range.


We have come to the end of this best penetrating oil review and you've seen the different offers out there, from the popular Kroil penetrating oil to the WD-40.

As you must know by now, different types of penetrating oil are good for different situations, including for merely cracking up rust, lubrication, and protection of the metal.

It's left for you, therefore, to make the right choice of penetrating oil, based on what you need it for.

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