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Have you ever been out trying to work on your car, only to be held up by nuts and bolts which seem impossible to remove? Well, this is where penetrating oil comes in. Not only is it useful in removing stubborn parts, but it can also be used as a rust penetrant, an adhesive remover, a metal cleaner, and a whole host of other useful functions. It is the kind of product which is used by DIYers, auto enthusiasts, and professionals alike.
However, if you have never looked into buying penetrating oil before, you will need some more information about which brand and type are going to be right for your needs. Our buying guide is here to help. Bear in mind that the wrong type of penetrating oil can end up damaging the surface which you use it on or may not do the job that you were intending effectively.
So, let’s run through 10 of the best penetrating oil on the market so that you can make a more informed decision about which one is right for your vehicle and any other tasks which you may need it for.
The Best Penetrating Oil
This Aerokroil penetrating oil promises to loosen even the toughest of stuck metal parts, penetrating to one-millionth-inch spaces. On top of its lubricating properties, it also helps to clean and prevent rust. Just a few of the parts which it can be used to pry free include nuts, bolts, pipes, bearings, flywheels, and sprockets.
If you have air tools which need lubricating and cleaning, this is a great product option. It also displaces moisture, removes rust, gunked up oil and grease. And since it is harmless to metal, you can also use it in a preventative capacity against rust.
Penetrates to one millionth inch space
Displaces moisture and prevents rust
Suitable for a range of jobs
- BrandKano Labs
- ModelFBA_AeroKroil 16.5
- Weight1.03 lb
Excellent cleaner for metal parts
Long-lasting rust protection
Lubrication in minutes
Dissolving effect on some materials
A brand which is well-known to everyone, this WD-40 spray comes with a smart straw which can be applied in two different ways. Flip it up for a stream or down for a penetrating oil spray depending on the job which you are trying to complete. Though it is just a single formula, it offers five different functions; lubricating, penetrating, protecting, removing and displacing moisture.
This is the kind of product which can be used for thousands of different purposes including in engines, on bikes, alloy wheels, and all types of nuts and bolts. A formula which has been trusted for over 60 years, it is safe on rubber, metal, wood, and most plastics.
Smart straw for two different application methods
Single formula; five different functions
Trusted for over 60 years
- Weight10.4 oz
Useful for thousands of jobs
Trusted formula usable on rubber, metal, wood, most plastics
Straw needs care and practice to use effectively
A trusted tool for DIY enthusiasts and professional tradespeople alike, this multi-purpose oil lubricates, cleans, and protects against rust and corrosion. The nozzle at the top is designed for a precise application process, making it perfect for use on sliding doors, power tools, wheels, external parts of small motors, nuts, bolts, and much more.
The packaging has been cleverly designed in a squeeze-bottle format to offer complete control over the amount of oil dispensed, while it also has a fill level indicator strip to let you know when you are running low.
Designed for automotive, marine, home, and shop use
Squeeze bottle with fill level indicator
Marksman Twist Spout for accurate application
- Weight8 oz
Lubricates, cleans and protects against rust and corrosion
Excellent penetration levels
Difficult cap to remove
Made using a fast-acting, anti-seize formula, this product from Liquid Wrench is designed to dissolve oil and cut through grease. It has been specially designed to provide maximum penetration, while also reducing friction and preventing wear. It is safe on metal, plastic, rubber and painted surfaces.
So, when you are working on your car and looking to free stuck nuts and bolts, this is a great product which you can turn to. It also features a precision spray straw for the easiest of application processes.
Usable on metal, plastic, rubber, and painted surfaces
Formula designed for the high level of penetration
- BrandLiquid Wrench
- Weight4.8 oz
Fast-acting, anti-seize formula
Versatile multi-use penetrant
Precision spray straw for easy application
Sliding down in those hard-to-reach areas, this PB Blaster has been created to start acting on surface tension rust and corrosion. And once you have applied it, a non-evaporating lubricating film is left behind to prevent rusting in the future, making this issue less likely to occur further down the line.
Ultimately, this is the kind of product that saves you both time and money as you will not have to either burn off or drill out nuts, bolts, and pipe threads.
Accesses hard-to-reach areas
Leaves behind the non-evaporating lubricating film
Effective on brakes, exhaust and suspension system jobs, plus nuts, bolts, and pipe threads
- Weight9.6 oz
Good for breaks and suspension systems
No straw makes it more challenging to apply
Another penetrating oil from Kano Kroil, this product offers the same guarantee of loosening frozen metal parts or you can claim a full refund. Since it loosens metal joints in just a few minutes time, it will save you significantly on labor and equipment. And while it will dissolve gum, dried grease, and oil, it will not attack the metal itself.
On top of all this, it is one of the best penetrating oils for rust and carbon deposits. Just a few of the tight parts that you can use it on include nuts, bolts, pipe threads, pulleys, and screws.
Loosens frozen metal parts
Dissolves grease, oil and gum without attacking metal
Attacks rust and carbon deposits
- Weight2 lbs
Gets to work in minutes
Useful for a range of different tasks
Excellent rust prevention
Temporary solution for lubrication as it doesn’t remain for a long time
Whether you are looking to penetrate through rust, scale, and corrosion or loosen up grease and carbon deposits, this deep penetrating oil will do the job for you. Perhaps the nuts and bolts around your car engine are impossible to remove or the muffler clamps and tail pipe have become blocked up with rust. Simply apply some of this formula and you can get everything back to the way it should be.
Since it doesn’t contain any silicones, it is usable in indoor environments such as a workshop. Ultimately, it takes away a lot of physical labor like hammering and drilling.
The formula to free up parts and assemblies instantly
Loosens up lead, tar, grease, carbon and graphite deposits
- Weight0.8 oz
Contains no silicones – suitable for paint and shop environments
Works faster than other solvents
Sometimes needs several applications for best results
This high-quality penetrating oil helps to lubricate a wide range of moving parts which have become tough to operate. Oil-based and blended from a patented formula, this product is specifically designed to release friction and inhibit corrosion.
Penetrating deep into metal pores, it also leaves behind a light and clearly a lubricating film which has a lasting staying power. And while it will not affect seal materials or coatings, it will protect against moisture.
Significantly reduces friction and wear
Fights rust and protects against moisture
- BrandSchaeffer Manufacturing Co
- Weight13.6 oz
High-quality penetrating oil
Reaches deep into metal pores
Releases friction and inhibit corrosion
No straw – application can be challenging
A lubricant containing PTFE and long-chain friction inhibitors, Andy’s Super Oil promises advantages over other similar products on the market including staying exactly where you spray it and lasting for a longer period of time.
Essentially, this is a useful product for a range of pursuits which rely on moving parts such as DIY, cycling, gardening, powersports etc. If you have squeaks which simply won’t seem to be silenced, this oil can play a central role in helping out with this. The special penetrating and foaming agents will penetrate deep down into the hard-to-reach cracks and crevices, repelling water wherever it goes. Thanks to its distillate base, the oil will stay only where you spray it.
Special formula containing PTFE and long-chain friction inhibitors
Proprietary foaming agents
- BrandAndy’s Super Oil
- Weight2.25 lbs
Suitable for a range of moving part rust and stuck objects
Used by pros and DIY enthusiasts alike
Delivers lubrication exactly where sprayed
Larger cannot easily transportable
Firstly, it loosens frozen metal parts. Secondly, it dissolves rust and corrosion. And finally, it lubricates and prevents rust.
Essentially, this helps in a range of tasks centered on machinery, tools, and equipment – everything from basic maintenance to emergency repairs. When you are loosening rusted and frozen components, the lubricating residue left behind plays a part in preventing corrosion.
Loosens stuck metal parts
Fights rust and corrosion
Lubricates and prevents further rust
- Weight1 lb
Suitable for simple maintenance tasks and essential repairs alike
Leaves behind lubricating residue to prevent corrosion
No straw – application not as precise as other products
Best Penetrating Oil Buying Guide & FAQ
Things to Consider When Buying Penetrating Oil
Before investing in a penetrating oil, there are a few essential considerations to make so that you choose the right one for your needs. Below, we have listed just a few of the factors which are worth thinking about in more detail.
- Suitability for the Surface
Since you are thinking about buying a penetrating oil, you probably have a specific surface or material in mind which you would like to use it for. It is worth bearing in mind that some oil can be damaging to certain materials, so make sure that it is suitable for the surface which you intend on applying it to. Most oils are suitable for metal, rubber, painted surfaces and many types of plastic. Beyond this, check the label or get in touch with the manufacturers directly.
- Type of Job
Many of the oils which we have discussed list the main jobs which you can use it for, so you should check this before making a purchase. For example, some oils are best at loosening, while others are most effective when it comes to cleaning or removing rust. Of course, there are also oils which are more multi-purpose and can be used in a range of different situations.
- Ease of Use
Obviously, if the penetrating oil is easy to use, it makes any task much more straightforward. Some of the above products come with straws or in spray format to make precise application easier. Others have a 2-in-1 format which allows you to use it as required. Accurate application is especially useful if you are trying to get to hard-to-reach places or you are doing a job which requires you to access a tight area.
Another issue which is worth bearing in mind is the viscosity of the oil which you are investing in. The best penetrating oil for rusted bolts have a lower level of viscosity tend to be able to penetrate deeper into joints which have become especially rusted over. If you use an oil with a higher level of viscosity, there is every chance that the stuck components will become even more damaged and will remain where they are.
After you have gone through the effort of unsticking the metal parts, you will want to avoid this issue reoccurring in the future. This is where the lubricating capabilities of the penetrating oil which you choose comes in. Good-quality penetrating oils should work by penetrating down into the thread, removing the rust, and leaving behind a lubricant which will help to reduce the risk of future rusting and corrosion.
- Environmentally Friendly
How environmentally friendly a product is to the environment is more and more of a concern to responsible buyers. So, you could look at the manufacturers which formulate their penetrating oil without ozone-depleting compounds. If you are planning on using the oil in a contained environment, it is also worth looking into the ones which are odor-free.
Price is obviously a central consideration for many buyers, but you shouldn’t immediately be drawn to the cheapest product as it is not necessarily going to be the right one for the purposes which you have in mind. Look at the different brands within your price bracket and compare the range of features which each one of them offers. Of course, it is not worth compromising on effectiveness for the price as you simply may not be able to do the job that you would like.
What Do You Use Penetrating Oil For?
There is no one single use for penetrating oil, but there are some common reasons why you would need a product of this variety. Here are just a few of the main ones for you to consider in more detail.
- Lubricating and Loosening Stuck Parts
The most common and obvious use of penetrating oils (for car enthusiasts, at least) is loosening mechanical parts which have become stuck through corrosion, rust or some other means. The reason why this type of oil is particularly effective in this type of job is its ability to penetrate the small gaps and crevices which are very difficult to reach through any other means. As well as easing the removal, it can also help to separate one part from another. Penetrating oils are low viscosity and can lubricate parts without resistance. They should also be effective on frozen water valves. All you need to do is apply it and leave it for a couple of minutes. The valve should turn a lot more easily after a couple of minutes.
Another function of penetrating oil is that it is a good cleaner and effective against corrosion. And many of the oils which we have discussed in this article work on a range of different surfaces. Of course, you should always check the label to make sure it is safe for your intended usage. Just some of the things that a good penetrating oil will remove as a cleaner include greases, spray paint, tars, chewing gum, permanent markers, and dripped varnish.
- Prevention Against Rust/Corrosion
It is very frustrating when parts become stuck together, which is why a lot of penetrating oil has the secondary function of leaving a penetrative film. This will help to prevent against future rust and corrosion, keeping your car engine or whatever else you use it for in good shape. Essentially, it helps to provide resistance against the common causes of rust and corrosion such as salt and water, acting as an anti-corrosive coating or a water repellent. So, you can use penetrating oil as part of your routine maintenance to prevent future rusting and corrosion.
- Quietening Noisy Parts
If you have a squeaky door hinge or a noisy suspension, penetrating oil can help out with this irritating problem. These oils solve this issue by reducing heat and friction, thereby lessening the noise between any parts which are squeaking or have become rusted over. However, before you get to work using it on a surface, make sure that you check to ensure that it is suitable.
Types of Penetrating Oil
Penetrating oil comes in a few different varieties, and you need to make sure that you take the time to choose the right one for the jobs which you have planned. Here is a quick overview of the main varieties to assist you in this task.
- Synthetic Penetrating Oils
Some of the synthetic compounds which can make up this type of oil include polyglycol, esters, silicone, diesters, and CFSs. As well as offering a high level of performance, one of the main advantages of this type of oil it that it is often more fire resistant. On the downside, it can cost a little more than the other varieties that are readily available on the market.
- Straight Penetrating Oils
Straight penetrating oils are the ones which tend to be commonly used on all sorts of mechanical applications. Generally, they are made from base mineral lubricants using esters, fats or extreme pressure additives such as phosphorous, sulfur, and chlorine.
- Emulsion/Water Soluble Fluids
With a low concentration or a high dilution, these oils are made up of high-water content fluids. Often, these are sold in a diluted version using a concentration percentage of upwards of 10 percent. And they can be used on some materials which may end up getting damaged with other types of penetrating oils.
- Micro Dispersant Penetrating Oils
This variety of penetrating oils have solid lubricant particles in a synthetic or natural oil base. The most common example of the solid lubricants used to make them include polytetrafluoroethylene, graphite, and boron nitride.
Homemade Penetrating Oil
While penetrating oils tend to be an affordable purchase which is indispensable when undertaking a range of maintenance tasks, you also have the option of making your own at home. One way of doing this is with a half-and-half mixture of acetone and automatic transmission fluid. However, this solution will have a very strong smell and is also a lot more flammable than the commercial products on the market. So, you should always use it outdoors and away from any flames. Not only this, but it won’t work as quickly as the products which we have discussed above.
Another option is to use vegetable oil with between 5 and 30 percent acetone depending on how strong you need it. Higher concentrations will allow you to unstick nuts and bolts which have become particularly frozen solid.
Best Penetrating Oil Buying Guide FAQ:
Q: What is Penetrating Oil?
A: Penetrating oil is a low-viscosity, petroleum-based lubricant which is mostly used for mechanical purposes, making it especially effective on automobiles. Generally, it is used to loosen up the parts which have become stuck through rust and corrosion, assisting in their removal and replacement. These oils got their name through their ability to penetrate into the narrowest of spaces, displacing other materials which are causing the problem and leaving behind a thin coating of oil in the surface pores. In the future, this should help to avoid the issue of sticking parts through its lubricating qualities.
The other main uses of penetrating oils include cleaning, lubricating, and preventing corrosion, and they are used in industrial and home environments alike. Car engines with a high-mileage can benefit from the penetrating oil for a seized engine as it will help to protect their moving parts, as well as standing the test of time in not freezing, melting or running off.
Penetrating oils may vary in their properties, but most of them should take effect within 15 minutes or less. The time will depend very much on the quality of the penetrating oil which you have chosen to use.
Q: Is Penetrating Oil Flammable?
A: A lot of penetrating oils have low flash points which cause them to have a high flammability rating. Therefore, you need to be especially careful not to use it around any flames or enclosed environments in which a spark may lead to a fire.
Q: What Does WD-40 Stand For?
A: WD-40 stands for water displacement 40th formula. The name is used from the lab book of chemist Norm Larson who first manufactured the product in 1953. It took him 40 goes to perfect the formula which is so commonly used today!
Q: Is Penetrating Oil Harmful to Plastic?
A: In the vast majority of uses, penetrating oil will not cause any harm to plastic products. However, certain types of plastic such as polyurethane can become dissolved or damaged. Always check the label and product specifications to ensure that the oil you have chosen is suitable for the material.
Q: Will Liquid Wrench Penetrating Oil Prevent Rust?
A: Yes. All Liquid Wrench lubricants are designed to help prevent metals from rusting.
Our Top Pick
Our pick of the bunch is this Kano Aerokroil Penetrating Oil. As it promises on the packaging, it will loosen even the stiffest of stuck metal parts or you can get your money back again. Just some of the metal items which it is effective on include frozen engines, nuts, bolts, pipes, valve guides, and sprockets. It is also useful if you need to lubricate and clean air tools, guns, rifle barrels, and tools. Alternatively, you can also remove rust, gummed oil, and grease using it.
This oil is harmless to metal, penetrates to 1 millionth inch spaces, displaces moisture, and is highly effective in preventing rust. 480 out of the Fortune 500 companies use it, and we are also throwing our own endorsement behind this fantastic product!