Reviews

Best Penetrating Oils: Loosen Jammed Bolts and Fight Rust

Loosen corroded bolts, stuck nuts, jammed pipes, rusted screws, and other stuck parts with our top picks for the best penetrating oil.

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BY Heather Fishel / LAST UPDATED ON June 13, 2021

If you’re tackling any kind of auto repair work, you’re bound to encounter a stubborn bolt, rusted fastener, or other types of jammed, unmoving parts and pieces. As your vehicle ages, critical components can become corroded or rusted — and that leaves them stuck in place, frustrating your attempts at repairs. Fortunately, there’s an easy solution to these frustrating encounters: penetrating oil. 

With a bottle of penetrating oil, you can lubricate even the most stuck-in-place bolts and other kinds of fasteners. This handy oil will even prevent metal parts from sticking and corroding in place altogether, keeping them moving freely. With a penetrating oil in your garage tool kit, you’ll be ready — and better equipped — to deal with nuts, bolts, and any rusted parts. If you’re looking for the perfect penetrating oil to keep on hand, we’ve got a list of the best options available.

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All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

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Benefits of Penetrating Oil

  • Lubrication. Most penetrating oils will offer temporary, if not long-lasting (some products have additives in their formula to increase the lubrication effect) lubrication to mechanical parts. The oil will help with reducing friction and will loosen frozen parts or tight bolts and nuts. 
  • Cleaning agents. Most penetrating oils can also be used as cleaning agents. They can effectively remove tars, greases, rust, and adhesives. The fluid will work as a solvent and will melt contaminants to a point where they are easy to remove using a tack cloth, a wipe, or a light abrasive.
  • Corrosion-resistance. Penetrating oils are created to protect metal surfaces from corrosion. Corrosion is the biggest enemy of metals used in constructing mechanical parts. The oil has a formula that works by displacing moisture, which is a big part of the elements that cause rust and lead to corrosion.
  • Noise reduction. Penetrating oils help to reduce rust and friction that often leads to squeaky door hinges, windshield wipers, a noisy suspension, screeching bike chain, and other noisy movable parts.

Types of Penetrating Oil

Water-Soluble or Emulsion Penetrating Oil

Water-soluble penetrating fluids have a high water content in their formula. They can also be diluted in water to get a concentration that’s lower than 10 percent. These oil types are best used for materials that can be damaged by highly-concentrated solvents with harsh chemicals in their formulation.

Synthetic or Semi-Synthetic Penetrating Oil

Synthetic penetrating oils are created from synthetic or semi-synthetic compounds such as polyglycol, silicone, diesters, esters, or a combination of water and synthetic fluids. These penetrating oils are more expensive than other products in this industry. However, synthetic oils are fire-resistant and great coolants.

Straight Oil

The products under this type are made from base minerals and petroleum oils. The products do not need any dilution to be used and may contain other lubricants such as esters, fats, and vegetable oils. In some cases, the oils will also have other additives such as phosphorus, chlorine, and sulfur, and are great for machine parts lubrication.

Top Brands

WD-40

WD-40 (Water Displacement-40) is a penetrating oil and water-displacing spray manufacturer based in San Diego, Calif. The company was founded in 1953 and has been providing penetrating fluids under the trademark name WD-40 since then. One of its best penetrating oils for seized bolts is the WD-40 Multi-Use Product.

Kano

Kano, officially known as Kano Laboratories, headquartered in Nashville, Tenn., is a company that focuses on producing specialty chemicals. The company boasts of selling its products to 480 of the Fortune 500 companies around the world. The Kano Kroil Penetrating Oil is one of the best rust penetrating sprays under the Kroil name and has been in the market since 1939.

B’laster

B’laster Corporation is a company that manufactures and distributes B’laster lubricants, rust inhibitors, penetrants, and other specialty fluids for industrial and automotive industries. The company was founded in 1957 and is currently headquartered in Ohio. This company offers some of the best penetrating fluids for stuck bolts and the B'laster Penetrating Catalyst is one of them. 

Best Penetrating Oil Pricing

  • Under $20: This price level is for the basic-level penetrating oils that are mostly the water-soluble type. Most won’t have a long-lasting lubrication effect but expect to find some of the best rust penetrants in the market.
  • $20 to $40: This mid-range price level holds a variety of high-end penetrants that offer both rust-preventive and water repulsion features, to subpar products with the least impressive features. The penetrants here could be either straight-oil or water-soluble products.
  • $40 and up: You will find high-end products here. Some of these oils in this category are similar to the ones in the cheaper categories only that they are offered in packs or in larger cans. However, most are synthetic and semi-synthetic penetrating oils.

Key Features

Lubricity and Viscosity

Lubricity refers to the ability of the oil to reduce wear and friction in moving parts. If you intend to use the product on mechanical parts, you should focus on penetrating oil with a longer-lasting lubricating action. Viscosity is the measure of internal friction of the fluid and ranges from thick to thin. A low viscosity product will penetrate tight spaces faster and will go deeper with only a few drops.

Temperature Tolerance

Penetrating oils vary pretty significantly in their temperature tolerance levels. Some of these oils are perfectly suited for high temperatures and a lot of heat; others are only able to handle a certain heat level. Before you choose any particular oil, check the temperature tolerance rating on the container or product description. If you need a high-heat product, a larger temperature tolerance is better. You’ll want to consider where you’re applying the oil too, as parts that generate a lot of heat will need a more stable, capable fluid.

Product Formulation

In addition to temperature tolerance, you’ll also want to consider a penetrating oil’s product formulation — or the ingredients used to actually make the oil. While most penetrating oils share certain ingredients in common, different formulas can include different additions or omit critical ingredients. For example, some oils are specifically formulated to be safe on rubber and plastic parts. Others, however, might damage these more delicate materials if they come into contact with the oil. Think about where you’ll be using your penetrating oil most often to decide what kind of formulation you need.

Non-Foaming or Low Foam

There are two common options when you’re picking out a penetrating oil: foaming or non-foaming. Both are a great choice, but the one that’s best for you will depend on how, exactly, you plan to use your oil. Foaming penetrating oils aren’t suitable for coolant or grinding applications. However, non-foaming penetrating oils — or even low-foaming formulas — are perfect for these uses. If you’re unsure where and how you’ll be using the oil within your car, it’s best to opt for a non-foaming or low foam product, just in case.

Other Considerations

  • Quantity. When buying penetrating oil, make sure you look at the capacity of the products you are interested in and compare with others in the same price range. Always go for larger cans if you intend to use a lot of oil. Also, choose products with no expiration date if you are going for larger quantities.
  • Convenience. A spray can that allows you to deliver a stream or a spray is the best option when it comes to convenience. Spray cans are easier to use and will deliver the oil faster and effectively. There are products that come with a straw for precision spraying. 
  • Environmental friendly. You should at least ensure that you buy penetrating oils made of eco-friendly ingredients. These products will not only play a part in conserving the environment, but they are also safe to use. Consider zero ozone-depleting compounds that are odorless.
  • Additives. Penetrating oils can be formulated with a number of different additives — and each additive is meant to handle a particular issue or offer a specific benefit. Extra pressure additives, for example, help prevent wear and tear. Corrosion inhibitors can eliminate corrosion that’s already present or prevent future corrosion from forming. Double-check the penetrating oils you’re considering to find just the right additives for the problems you need to tackle.
  • Flash Point. A penetrating oil’s flash point is the temperature at which the fluid itself evaporates into a flammable gas. Like temperature tolerance, flash point is critical because it can make certain oils more volatile and likely to combust. If you’re concerned about temperature, make sure to choose a penetrating oil that has a higher flashpoint so it’ll stay stable even in the face of scorching vehicle temperatures.

Best Penetrating Oils Reviews & Recommendations 2021

Best Overall
B'laster BLP16-PB 12 oz. Penetrant

Whenever you’re dealing with mechanical parts or components, you need them to be clean in order to work efficiently. When parts are clean, every mechanical part works as it is meant to. If you are looking for a bio-solvent penetrating oil that will clean up parts and also ensure they are protected, it's the B’laster BLP16-PB. It has one outstanding feature: the ability to dissipate rust and corrosion on metal parts.


Once you apply this oil, it will get rid of the rust and the corrosion. Like the best penetrating oils, it can penetrate very small openings for an effective clean. The oil is specially designed to loosen bolts and nuts that are extremely hard to open. However, the amount of time it takes to loosen parts will depend on the rust and corrosion buildup. On average, it doesn't take more than a couple of minutes. And since it is sprayable, it is a lot easier to apply.


This penetrant has a nozzle with a small opening that ensures none of the product is wasted. You only need to spray a small amount for it to work. However, the fumes it produces when applied can be a little overwhelming, so avoid using it indoors. The can is also not very well-constructed and may shatter on impact when you drop it on the floor.

Best Value
3-IN-ONE 10038 Multi-Purpose Oil

Developed in 1894, this multipurpose drip oil is loved by many tradesmen and DIY enthusiasts. It lubricates and cleans parts and protects them against rust and corrosion. Its small nozzle makes for precise application and ensures there is no splatter or overspray. You can use it on small motors, sliding doors, wheels, casters, chains, bicycles, nuts,  bolts, power tools, and many other moving parts. It is also a powerful tool for removing dirt and grime.


You can never go wrong with this multipurpose oil, as it can be used for a variety of tasks in both residential and commercial environments. At home, you can use it on door hinges, faucets, and fans. We love the fuel level indicator strip that allows you to see exactly how much oil is left. You will also appreciate the fact that it comes in two sizes: 3 ounces and 8 ounces.


However, we have a few negative comments about this oil. For starters, the new can is not very user-friendly and does not dispense oil as it should. The oil pours out of the spout instead of coming out in drops. The cap is also fixed very tightly and is difficult to open. You'll have to use some force, which may cause the oil to gush out.

Premium Pick
Kano Kroil Penetrating Oil

One of the things we love most about the Kano KROIL Penetrating Oil is its ability to penetrate extremely small spaces. It can penetrate spaces so small they can't be seen by the human eye—like one millionth of an inch. It is one of the best oils for rusted components and you only need to use a little of it to see results. The oil loosens rusted or frozen nuts and bolts in a couple of minutes. It was developed by chemical engineers and is highly versatile. It not only works on mechanical parts, but it can also be used on electrical parts.


This penetrating oil can stop squeaks, loosen joints, prevent corrosion, and displace humidity and moisture (which are the main causes of rust). And since it has low viscosity, it easily creeps into confined spaces to do its best work. We also love the fact that it doesn't dissolve quickly and continues to lubricate parts a while after it has been applied. It does not damage the molecular structure of an object and can be used on aluminum and brass.


However, we are not too happy about its price, which puts it out of reach for many people. The container also bends easily and is not of the highest quality. And since it doesn't have a small nozzle, you may use more of the product and buy a new one sooner than you expected.

Most Versatile
Liquid Wrench Penetrating Oil

Liquid Wrench is a family-owned company that's been operating since 1941. The penetrating oils, lubricants, and greases the company manufactures help industrial and automotive professionals to solve all types of problems, from everyday ones to extraordinary ones. The Liquid Wrench L104 quickly dissolves rust and cuts through grease. You can use it to free any stuck bolts, nuts, and locks.


Whether you need to clean the residue of adhesive stickers or free mechanical parts from rust, this penetrant will do a great job. It has the ability to penetrate into the tiny spaces where threads of rusted parts meet. It has low surface tension which allows it to easily creep into rusted parts. The penetrant does not have a bad odor and is safe to use on painted surfaces. It also contains no volatile organic compounds (VOCs).


Before you use this penetrating oil, shake it well, then spray it liberally on the rusted parts. A few drops will go a long way. However, it comes in a small 4-ounce can and may not be sufficient for you if you’re a professional who spends a lot of time dealing with rusted parts and components. And compared to other penetrating oils of the same size, it is more expensive.

Honorable Mention
B'laster 16-PB Penetrating Catalyst

This penetrating catalyst is sold in a pack of two, so you can use it for longer. It is specially designed to penetrate and loosen rusted or frozen metal parts. It has been on the market since 1957 and is loved by many professionals and DIYers. Its non-evaporating lubricant reduces friction between surfaces and prevents further rust and corrosion.


Don't let rust and corrosion spoil your tools and equipment. With this penetrating catalyst, you can salvage rusted parts, lubricate squeaky and stuck machinery, and prevent further corrosion.


What you will love about this penetrating catalyst is that it can be used on a variety of objects, from rusted nuts to brake calipers. The oil quickly breaks rust bonds and loosens frozen metal parts. It can be used on cars, boats, and industrial parts. Some plumbers also use it in place of plumber’s grease. It can easily lubricate a kitchen faucet that's stuck.


However, it’s worth noting that the oil has an overpowering smell. It’s best to apply it after opening your home’s doors and windows. Also, the amount of lubrication it offers is not as good as what the best penetrants offer. Applying the product on small parts is also difficult because the can does not come with a straw.

Honorable Mention
WD-40 Easy Reach

No matter what you plan to do with your penetrating oil, versatility and convenience are two critically important features — and WD-40 Easy Reach offers both. 


WD-40 is a classic oil, and it’s known to be so versatile it can fix anything that squeaks, sticks, or needs added moisture or lubrication. And it’s a fantastic formula to use for auto repairs too. Specifically, WD-40 Easy Reach makes it simple to get the oil right where it’s needed, without worrying about breaking the slim hose included on traditional cans of WD-40.


With Easy Reach, you’ll be able to clean away corrosion and protect your vehicle’s various parts and mechanisms. It’ll free up sticky components, lubricate stubborn bolts and screws, and displace any moisture that’s causing problems. And thanks to the 8-inch bendable straw that’s attached to the canister of oil, you’ll be able direct the spray and apply it in targeted areas. It’ll even reach right into slim, tough-to-access areas that you can’t get to with your own hands.

Honorable Mention
B’laster PB Penetrating Lubricant

One of the things most people consider when buying a penetrating oil is the viscosity. Viscosity measures the internal friction of a fluid. It also refers to how easily oil pours at a specific temperature. Oil that is very thick may have a lot of surface resistance and may not creep into parts and components as rapidly as you would want.


The B'laster PB Penetrating Lubricant has low viscosity and easily penetrates into parts without any issues. It can be used on marine instruments, automotive parts, industrial machinery, and other equipment. If you are a plumber, you can use it to loosen faucets and other plumbing fittings.


This penetrating lubricant is sold in a pack of three, so you will get value for your money. After applying it, it leaves behind a lubricating film to prevent rusting and corrosion in the future. But you may not like the odor it leaves behind. The can may also run out of pressure before the product is finished. And you have to be careful when using the can; it may get dented or shatter if you happen to drop it.

Honorable Mention
Liquid Wrench L116 Penetrating Oil

Liquid Wrench is a family-owned company based in Charlotte, N.C. It has been developing products for more than 75 years and its commitment to innovation and quality has earned it the trust of both tradesman and avid DIYers. So, if you are in the market for a penetrating oil that can cut through grease and quickly dissolve rust, the L116 may be the answer to your needs. You can use it on bolts, hinges, rusted nuts, pipe fittings, clamps, locks, latches, and  much more.


The L116 Liquid Wrench Penetrating Oil is also ideal for frozen parts and hose pipe fittings. It does not have a powerful odor that overwhelms and contains no volatile organic compounds. It’s rare to find a penetrating oil that is gentle on plastic and PVC, but this one is. You can also use it on painted surfaces and it won't damage them. It is a fast-acting, anti-seize formula with low surface tension, low viscosity, high solvency, and high lubricity. It easily cuts through the toughest of rust. Knowing which penetrating oil to use is key to having great results. The L116 has all the features that experts look for in penetrating oil.


However, you may not like its smell, which lingers after application. Its nozzle is also not well-built and may break after a short period.

Honorable Mention
Sea Foam Deep Creep Premium Penetrating Oil

If you’re searching for a penetrating oil that’ll get deep into crevices and eat away at the gunk that’s causing you frustration, Sea Foam Deep Creep Premium Penetrating Oil is just the right product. This extra-tough and extra-capable oil is a premium-grade lubricant and penetrant, designed to get in deeper and work harder where it’s needed most. And it can offer long-lasting lubrication to prevent future issues.


Spray this Sea Foam penetrating oil where it’s needed, and it’ll get to work cutting through rust and other types of buildup. It can loosen and lubricate, and once it’s applied, it’ll also help protect your car’s parts and components. Formulated with a blend of petroleum-based ingredients, it’s gentle on polymers and resins yet tough on corrosion. It’s also quite stable, able to resist evaporation and keep its liquidity in the face of extreme cold or heat. 


Another perk is the versatility of this penetrating oil. In addition to working on vehicle parts, it’ll also do the same job on other metal parts, tools, hinges, rollers, slides, and more.

Honorable Mention
Dupont Teflon Penetrating Oil

Dupont Teflon Penetrating Oil is a high-performance product — and it’s one that can combat even the toughest types of corrosion. If you live near the ocean or face a lot of moisture and salt where you reside, this is the oil you need to tackle salt and the corrosion it causes. Specifically formulated to offer a high level of protection against rust and corrosion, this oil features a low odor and can dissolve rust even in salt-heavy environments.


Put this penetrating oil to work, and it’ll go on wet. It immediately gets to work dissolving rust, and it lubricates and delivers protection as it tackles your most imperative (and frustrating) problems. Safe for use on rubber components like O-rings, this oil can be used on bolts, nuts, threads, piping, valves, and other auto parts. 


With a high temperature stability and good water resistance, it’ll hold up and perform its critical job even when faced with unexpected elements.

Tips        

  • If you are dealing with a stuck bolt that won’t come loose even after using the penetrant, use a heat gun to warm up the bolt and it will automatically expand. You can then wrench it out. However, make sure the penetrant has a high heat tolerance, or keep the heat at a moderate temperature. Do not ignite the bolt if you used a petroleum-based oil to loosen it.
  • If you need to use the penetrating oil often, go for larger quantities. Most people do not realize that penetrating oil is available in large quantities because most brands only market smaller cans.
  • If the penetrating oil container does not come with a precision straw, you can always get an aftermarket option. There are precision applicators sold separately and will help you deliver the oil in tight spaces. You can also convert a syringe and needle into a precision applicator.

FAQs

Q: How long does it take for penetrating oil to take effect?

In most cases, you will have to wait for about 15 minutes for the oil to work effectively. It will, however, depend on the quality of oil and what it’s penetrating. Some penetrants will even need a whole hour and some wrenching to get the nuts loose. Using precision applicators can however reduce the action time.

Q: Does penetrating oil provide lubrication?

Yes. Most penetrating oil products provide some kind of lubrication. The problem is that the lubrication will not last long and you may have to use other lubricants. There are, however, penetrants with more lubrication properties than others.

Q: Are penetrating oil products flammable?

A good number of penetrating oil products have low flash points that lead to high flammability. This means that the products cannot be used on hot or fiery surfaces. However, there are some products that have high-temperature tolerance and can remain stable in high-temperatures surfaces like an engine.

Q: Can the penetrating oil be used on aluminum parts?

Unless specified, most penetrating oils will work well with all metals. You can effectively apply the oil on seized aluminum parts and get great results. It is always important to check on the instructions from the manufacturers to see on which surfaces the oil can or cannot be used.

Final Thoughts

We’ve chosen the B'laster BLP16-PB 12 oz. Penetrant as the best penetrating oil. It works on a variety of components and does not harden or lose its penetrating ability. 

Our choice for the best value penetrating oil is the 3-IN-ONE 10038 Multi-Purpose Oil. It’s a hard-working spray that penetrates deeply and quickly.