What is the best Penetrating Oil?

Nothing annoys car owners and auto mechanics more than rusted nuts and bolts that won't move. Any slight effort to force them out might damage the bolts, tool or machine part.

You might be tempted to reach for any lubricant oil available. No, don't do that! Using general lubricants with high viscosity would make matters worse. Such lubricating oils could, at best, get little rust off the surface without aiding the removal of the bolts and well, at worse, damage the metal surface. Extra care is needed when buying penetrating oil and this guide will help you make the right choice.

Why Penetrating oil?


As noted earlier, general lubricants cannot get you the desired results when it comes to removing rusted nuts and bolts. The best penetrating oil is one that has a low viscosity.
The low viscosity of penetrating oils or fluids allow them to:
    - get in between tight spaces
    - reduce the friction between bolts and machine parts
    - remove damaging rust from the metal surface quickly. 

Another feature of penetrating oil is high volatility, which makes it less suitable for general purposes like lubrication. Penetrating oils could also serve as chewing gum or adhesive sticker remover.

Few examples of the best penetrating oils are WD-40 490026 Multi-Use penetrating oil, Kano Aerokroil, Gasoila Free Rust Eater, and liquid Wrench L134-4PK.

Can WD-40 be used as penetrating oil?

Brief History

WD-40 is an acronym of water displacement, 40th formula. The water displacing spray was invented by an American industrial chemist, Iver Norman Lawson after the 40th attempt (hence, the name WD-40). Sometimes, the press mistake Norman Larsen, the then-president of the rocket chemical company, for Norman Lawson, due to the similarity in name. Even though Larsen was responsible for the idea of packaging the water displaying chemical, the original formula was designed by Lawson.

Before WD-40 became a large-scale consumer product, it was used by Caviar in the maintenance of Atlas missile. In 1961, WD-40 was officially labeled as a consumer product. 

1965 saw the application of WD-40 in the aviation industry. Airlines, such as United and Delta applied WD-40 on the rust-prone parts of their DC-8 and Boeing 720s.

WD-40 was not made available to the English farmers and mechanics until 1969. 1973 was a remarkable year for the public as the WD-40 company (previously known as the rocket chemical company) made the product available to everyone. 

Constituents of WD-40

The formula of WD-40 was never disclosed nor patented, since patenting the product would only buy more time instead of insuring their position as the only producer of the chemical. Though the formula remains unknown, the content was researched and exposed in a US material safety Data Sheet report.

The composition of WD-40 includes, 50% aliphatic hydrocarbons, 3% CO2, 9% inert gases, 18% low vapor pressure aliphatic hydrocarbons, and 25% petroleum oil. Opposite to the claim that WD-40 is similar to Stoddard solvent due to the presence of 50% aliphatic hydrocarbons, the company’s site debunked the claim.

Low vapor pressure aliphatic hydrocarbon was added so as to lessen the chemical’s viscosity or thickness. This report explains the reason for the high volatility of WD-40. As a result of the low viscosity, WD-40 is suitable for aerosols.

Co2 serves as a propellant, which reduces the flammability of the WD-40 products. It is important to mention that the original version of the WD-40 had no propellant.

In addition to the US Material Safety Data Sheet Report, Germans also published their version, which replaces aliphatic hydrocarbons with 60-80% hydrogen-rich naphtha. Naphtha is a popular petroleum product found in wick-type cigarette lighters

The reports further noted that the content of WD-40 is not skin-friendly. When exposed to the skin, it can cause severe skin irritation and it could damage the eye. 

WD-40’s ability to serve as a penetrating oil

WD40 is a penetrating oil, water displacer, and rust buster. Originally, WD-40 was introduced 66 years ago, as water dispersant. Its lubricating feature is linked with its ability to dissolve rust. Unlike lubricants, it is hygroscopic and should not be used as an everyday alternative to general lubricants.

Nicknamed rust buster, WD-40 is often touted as the ‘fluid for a thousand jobs' because of its multi-purpose features. It can be used for all tools except guns and gears due to its high hygroscopic properties. 

What are the primary and secondary uses of penetrating oil?

Primary Use: for rust removal, corrosion prevention and water displacement

Penetrating oils are well designed for rust removal. Ten minutes after spraying the tool with penetrating oil, the oil would enter the tight areas and dissolve the rust. To prevent metal scratches, the oil action should be aided by applying soft-bristled brush on the metal surface.

After applying penetrating oils on a metal surface, the residual substance would prevent the further accumulation of corrosive substances like salt and water. 

Secondary use: In place of a lubricant and in the reduction of noise from stiff parts

Though penetrating oils are volatile, they leave a lubricant residue after vaporizing. This lubricant residue, in combination with the dissolved substances, could reduce the friction in the tools, but using penetrating fluids as general-use lubricants is not advisable.

You don’t have to endure noise pollution from a squeaky door hinge or noisy suspension once you’ve got penetrating oil. By reducing the frictional stress and heat between the tight regions of the hinge or suspension, penetrating oil gets rid of noise pollution in minutes. It is pertinent to mention that some penetrating oils might not be suitable for some metals, so check the label to see the manufacturer’s exceptions and recommendations.

Why is penetrating oil good for rust removal?

Penetrating oils are made up of hygroscopic chemical substances such as lower alkyl benzenes, lower alcohols, methyl silicone and many more.  The hygroscopic characteristics help it disperse water, a popular rust-promoting agent. In addition to the dispersal of water, the penetrating oil leaves an anti-corrosive coat, which serves as a salt and water repellent. 

The major selling point of penetrating oil is its ability to find its way into tiny gaps and crevices, enabling it to act on areas where general lubricants cannot reach. When separating parts from one another, it is advisable to first apply penetrating oil on the stiff parts.  With the goal to ease removal and prevent damage by surface scratching.
Due to their Alkyl chemical properties, penetrating oils could also be used to unfreeze a frozen water valve. All you need is to put some penetrating oil on the water valve and let it work for some minutes. The temperature of the frozen water valve should increase after a few minutes thereby unfreezing the water valve.

After applying penetrating oil on a metal, it leaves a penetrative film on the applied surfaces. This penetrative film has anticorrosive properties, which prevents further corrosion and extends the lifespan of your tool, door hinge or car part. Also, the penetrative film boosts the metal’s resistance to substances that promotes the process of rusting, such as dust, salt and water. The penetrative film is also called a water-repellent coat.  

What is Nano-Spray™?

CleanBoost® Nano-Spray™ is an advanced penetrating oil that removes rust from tools and machines regardless of how tight the spaces between the orifices, bolts and gears. It is a perfect alternative for lubricants that work superficially. It is designed to aid the loosening of bolts and nuts; form an anti-corrosive layer on the metal; prevent the wear and tear of metal surfaces due to friction; and help drill bit performance.

Why it works better than other lubricants?

CleanBoost® Nano-Spray™ is modeled to perform the functions of a lubricant, coolant and also serve as an anti-corrosive agent. While increasing the lifespan of drill bit with its cooling effect, it also quickens the process by conserving the time used to fix rusty parts. It was originally designed for large-scale manufacturing process, but it is now sold in easy-to-handle 16 ounces bottles. The manufacturers of nano-spray are concerned about the safety of the users and they avoid the use of harmful chemicals.

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Tech Guy

Automotive enthusiast, passionate about Jeeps, hot-rods, turbos, performance, efficiency, diesels, fuels, high performance oils, additives and anything with an engine.

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