8 Best Penetrating Oils for Rusted Bolts

Have you ever tried to remove a bolt from a car only to find it welded in place due to rust or old age? If you have, then you understand how much one stubborn bolt can slow you down in the garage.

Having a high quality penetrating oil can save you time and effort and make the process of removing bolts, screws and nuts, a cinch. Here are 8 of the best penetrating oils to remove rusted or seized bolts to avoid wasting money on worthless products.

Top 8 Best Penetrating Oils to Remove Seized Bolts

1) Kano Aerokroil Penetrating Oil

best penetrating oilFor the toughest rusted bolts, it’s hard to beat Aerokroil. Made in Nashville, TN, It’s arguably the best penetrating oil ever made despite it being one of the pricier oils on the market.

Aerokroil is an easy to use aerosol and patented lubricating technology eases tension in all metal joints, reducing friction with ease by penetrating through rust but leaving the base metal beneath untouched.

There’s good reason why professionals trust Kano Aerokroil over any other penetrating oil when dealing with the most stubborn fasteners (including on car and truck exhaust components). As mentioned, it’s not cheap so it may be overkill for some applications.

2) B’laster Penetrating Catalyst

B'laster penetrating oilB’laster is another well-known penetrating oil product due to its price point and effectiveness. While it may not work as well as Aerokroil for the most stubborn rusted or seized fasteners, it still gets the job done more often than not.

A problem that’s commonly associated with penetrating oils is how they evaporate quickly, thus making them ineffective to lubricate surfaces long term. B’laster is different as it creates a non-evaporating film that remains on surfaces longer and provides a lubricant for moving parts.

3) Liquid Wrench Penetrating Oil

Liquid WrenchMade in the USA, Liquid Wrench is one of the best regarded penetrating oil brands in the world, and L212 11-ounce can is easily one of their most well-known products.

As far as rust removal goes, Liquid Wrench has unmatched performance, and its patented formula has seen many improvements over the years resulting in the respected product it is today.

Whether you want to lubricate moving parts, free a rusted bolt, unfreeze a lock or get rid of the grease within a pipe or hose, Liquid Wrench can tackle it all.

4) Gasoila Free All Rust Eater

Gasoila Free AllGasoila Free All spray is made with adaptability in mind. Whether it’s a hinge, bolt, fence, gate, or any other metal object, this rust removing penetrant will not only remove the rust, but free the object too.

On top of this, Gasoila Free All deep penetrating oil is incredibly good at getting rid of white and red lead, carbon, graphite, tar deposits and scale.

On top of that, Gasoila Free All doesn’t contain silicones or other harsh chemicals, making it safer for the environment than some of its competitors.

5) CRC Knock-Er Loose Penetrating Solvent

CRC penetrating oilAs one of our favorite fuel system cleaners, CRC has another good product on their hands. CRC Knock-er Loose is a real powerhouse.

The patented formula features a mixture of chemicals that will lower the surface tension on every rusted or jammed metal item you throw at it whilst protecting the metal underneath.

Because of its incredibly low viscosity, this solvent is able to reach into the tightest of spaces, loosening and lubricating surfaces with ease. CRC Knock-Er Loose is a great option for loosening rusted or corroded bolts and frozen metal components.

​6) Castle Thrust Penetrating Oil

Castle Thrust penetrating oilThe unique selling point of Castle Thrust Penetrating Oil is it’s a unique ion activated formula that prevents it burning off making it highly effective on metal parts subject to high temperatures.

This foam based solvent sticks to metal with ease and penetrates even the smallest of gaps making it ideal for auto-mechanics.

Because it’s not as well-known as some others, Castle Thrust penetrating oil is a bit tougher to find. But make no mistake, it can loosen some of the most stubborn nuts and bolts and is a good alternative when lesser products fail.

7) WD-40 Specialist Penetrant

WD-40 Specialist reviewWD-40 is one of the most ubiquitous multipurpose products ever made. Its many applications, ranging from lubricating metal surfaces to removing rust, have seen it sell millions of cans all over the world.

The name WD-40 stands for “water displacement 40” and was created to protect aircraft and rockets from rust. WD-40 is a great product for displacing moisture and as a result penetrating through rust and protecting it from forming. This “Specialist” spray is specially formulated to penetrate rust and corrosion to get the toughest nuts and bolts unstuck.

The can comes with a permanent straw attached and its unique two-way spray system allows it to be used upright and upside down allowing it to reach places other lubricants cannot reach. WD-40 Specialist is the perfect choice for an all-purpose lubricant and penetrating oil for around the house.

8) 3-IN-ONE Multi-Purpose Oil

3-in-1 multipurpose oilThe 3-IN-ONE Multi-Purpose Oil is one of the oldest penetrating oil brands on the market (since 1894) and as a result has benefited from years of experience and tinkering by its manufacturer.

This multipurpose drip oil can be used by both DIYers and mechanics and has a wide range of functions, including lubricating, cleaning and protecting metal tools, and clearing and preventing rust. While inexpensive, the 8 ounce container of 3-in-One oil goes a long way.


9 thoughts on “8 Best Penetrating Oils for Rusted Bolts”

  1. I’ll swear by it till the day the good lord calls my name. Just regular WD-40 is great. If that doesn’t get it off you need to use heat and that’s a fact.

  2. How do you know the above work well? Did you do any actual testing, or did you just accept their advertising statements? If you did do testing, is there somewhere we could review your results?

    Sorry to be a skeptic, but I think your readers are entitled to full disclosure.

    • Fair question. Any products we recommend are based on a combination of personal experience with a product (when possible) along with data from various online sources including product pages and forums. We don’t claim to be a product review website (ie: Consumer Reports) that does hands-on testing of every single product mentioned.

    • I have used Kroil and PB Blaster in my shop. I don’t even own WD 40. Something else that works is Wintergreen oil. Just a little bit goes a long way.
      Twisting things off is a lot worse than investing time.
      Tho sometimes, that’s just gonna happen.

  3. one of the best ‘ol timers in rust penetrant is the cnh insustrial strength rust penetrant! think it’s made in canada. try it you’ll like it! gerald, oklahoma


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