Reviews

Best Rust Prevention Spray for Cars: Boost Your Car’s Lifespan 

Give your car the rustproofing and protection it needs.

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BY Norah Tarichia / LAST UPDATED ON April 9, 2021

Most scratches, minor dents, peeling, or flaking paintwork are minor flaws that you can correct without using many tools. However, there’s nothing more tedious than removing heavy scaly rust from your vehicle. You may need to use a combination of heavy-duty sanding tools and rust-removing agents to restore the look of your vehicle—that is if the rust hasn’t done so much damage that you need to replace the part. The best way around this is that you shouldn’t leave it until it’s too late. Even before you start seeing signs of rust, treat your vehicle with a rust-prevention formula. You can conveniently do so with a rust prevention spray, where with just a few spritzes, you will create a sealed finish that blocks moisture and prevents oxidation. What’s more, most of these formulations also act as rust removers or converters. So if you’re looking to keep your car in tip-top condition, this guide is a great starting point.

Best Overall
BOESHIELD T-9 Rust & Corrosion Inhibitor
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Summary
Summary

This formulation doubles as a rust inhibitor and a waterproof lubricant and is safe for any metal, plastic, or vinyl surfaces. It comes in a 12-ounce bottle.

Pros
Pros
  • Effectively penetrates moving parts for lubrication 
  • Leaves a thin waxy film for prolonged protection 
  • Loosens rust and flushes out old lubricants 
  • Safe for bicycles, marine, and automotive equipment
Cons
Cons
  • Leaves a messy finish that needs to be rubbed in for a neat appearance
Best Overall
BOESHIELD T-9 Rust & Corrosion Inhibitor
Best Value
Rust-Oleum Rust Reformer Spray
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Summary
Summary

This oil-based formulation comes in a 10.25-ounce bottle and works by loosening rust and preventing further corrosion.  It takes about 20 to 40 minutes to dry.

Pros
Pros
  • Affordable solution for eliminating rust on any metal surface
  • Doesn’t chip or flake once it’s fully cured 
  • Converts a rusty surface to a paintable surface
  • Spray can is fitted with an any-angle-spray that can be sprayed in any direction
Cons
Cons
  • Nozzle opening may clog up with time
  • You may need more than one bottle to cover your vehicle's exterior surfaces
Best Value
Rust-Oleum Rust Reformer Spray
Honorable Mention
 Permatex Rust Treatment (Pack of 12)
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Summary
Summary

Coming in a 12-pack, this spray-on rust treatment dissolves rust within minutes and leaves behind a protective primer to keep rust from forming.

Pros
Pros
  • Application is very easy—simply spray it or brush it
  • Can be used on all automotive parts
  • Leaves behind a long-lasting coat that can be painted over
  • Dries within minutes when sprayed in small patches
Cons
Cons
  • Has an overpowering smell 
  • You need to apply another primer over it before painting to prevent blistering
Honorable Mention
 Permatex Rust Treatment (Pack of 12)

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Benefits of Rust Prevention Spray

  • Saves money. Rust can cause serious problems with your vehicle, and treating accumulated rust is an expensive venture. Rust-proof spray for cars ensures you tackle the problem before it becomes a big financial drain. 
  • Maintains the resale value. Rust damages your car, lowering its value. If you protect your car against rust, you may get a better offer because it looks good and runs smoothly. 
  • Improves durability. Cars eventually wear down over time. Keeping yours rust-free is one way to make sure it gives you great service for a long time. 
  • Reduces accident possibilities. Anti-corrosion spray for cars ensures that all parts of your car are well-maintained and functioning properly. If every component works as it should, chances of mechanical failure and accidents are minimized.

Types of Rust Prevention Sprays

Inhibitors

Inhibitors are specially designed to prevent rust on surfaces. They slow down the process of oxidation, which leads to rust. They should be used before rust appears, and the best rust inhibitors for cars are a great preventive measure, especially in humid areas.

Removers

Removers are considered some of the best rust-proofing sprays for cars. This is because, unlike inhibitors, you can spray them directly on rust. They bond with rust, and the resulting substance can be washed off with soap and water. You can also use removers as inhibitors. 

Primers

Primers form a base, which is a treated surface you can paint over. They are usually combined with removers to create powerful rust prevention sprays. Primers are bonding agents that create a bond between the surface beneath them and the paint applied on top. Their main job is to make the paint stick well to the surfaces.

Top Brands

3M

3M was founded in 1902 as Minnesota Mining and Manufacturing Company. The discovery of a low-grade mineral transformed the company into a global innovator with brands and products in more than 10 key industries. Today, it is a hugely successful company known for products such as Professional-Grade Rubberized Undercoating

Rust-Oleum

Founded by Robert Fergusson in 1921, Rust-Oleum has a track record of manufacturing some of the best protective paints and coatings for home, automotive, and industrial use. It’s a subsidiary brand of RPM International Inc. and is headquartered in Vernon Hills, Ill. One of its best-selling rust converter and prevention spray is the Rust Reformer Spray.                                                                           

VHT Paints

VHT Paints is a subdivision of Dupli-Color, which has been manufacturing automotive care products since 1938. VHT stands for Very High Temperature, which is a reflection of what its products are designed for. It’s a manufacturer of automotive paints, rust treatments, and coating systems that can withstand being used in high-heat applications. 

Permatex

Since 1909, Permatex has been at the forefront of the automotive industry. It produces car products for both residential and commercial use. It’s a trusted brand with a presence in over 80 countries. One of its best-selling products is the Rust Dissolver Gel.

Rust Prevention Spray Pricing

  • $5-$10: If you are on a tight budget, this is a great place to start. A spray in this price range works as a rust converter for any metal surface. 
  • $11-$20: There are more options in this price range. Sprays come in 12- to 16-ounce cans and leave a clean finish. 
  • $20 and up: Some of the best undercarriage rust protection products come in at this price point. Most rust preventers that cost over $20 can be painted over. Some manufacturers sell two or three sprays in a pack, so you get great value for your money.

Key Features

Corrosion Resistance

A rust prevention spray must have corrosion inhibitors to help protect your vehicle from the effect of daily wear that comes with living in a humid environment. Ideally, it should leave a long-lasting protective film that keeps out moisture and prevents oxidation to preserve the quality of the metal.  

Drying Time

The drying time separates the best rust stoppers for cars from the worst. You need a treatment that takes only a few hours to settle and dry. This is important if you are considering painting over the area. If the spray takes too long to dry, you may have to wait for hours — or days — before painting your car. 

Other Considerations

  • Quantity. You need to consider how large the surface is so you can decide if one bottle is enough. For example, to treat large surfaces such as the car hood or the doors, you may need more than one bottle to get the job done. 
  • Color. Some formulations may leave behind a black matte finish when they dry, while others may leave a transparent film. The former can help you easily identify the areas that have been left untreated. However, if you intend to paint over the surface, prioritize sprays that leave a transparent layer. 
  • Type of Surface. You need to consider the type of surface the formulation is designed for so you don’t end up corroding it. For example, some formulations are only suitable on metal and may corrode fiberglass, vinyl, or plastics. However, you can find multi-purpose formulations that can be used to treat rust on any surface. 

Best Rust Prevention Sprays Reviews & Recommendations 2021

Best Overall
BOESHIELD T-9 Rust and Corrosion Inhibitor

This rust and corrosion protection spray was designed by Boeing to lubricate and protect aircraft parts. It is designed for automotive, marine, and aviation use and other applications. It's safe to use on paint, metal, plastic, and vinyl. The product loosens rust, dirt, and old lubricants and dries into a thin, durable film. This spray works well on cars, trailers, lawnmowers, and anything else that requires lubrication or protection against rust. You can spray it under the hood of your vehicles to coat anything that might rust or use it on tools, lawnmowers, and snow blowers before they go into storage. It puts a great rust barrier on naked steel, goes on clear, and doesn't rub off.


The biggest complaint with this product is that while it sprays well initially, it tends to clog up before you're done with the can. Also, it's a little pricey, and the finish may be a bit tacky unless you rub it down a little.

Best Value
Rust-Oleum Rust Reformer Spray

The aging and rusted metal components of your vehicle, including corroded battery terminals, can benefit from the Rust-Oleum Rust Reformer Spray. This oil-based formulation works by bonding with rust to convert it into a rust-resistant, flat-black surface that can be painted over. It dries in about 20 to 40 minutes and forms a permanent coat after 24 hours. The coat prevents further rust from forming, and it doesn’t flake or chip even if you don’t apply a topcoat. The bottle is fitted with an any-angle spray nozzle with a comfort tip so you can comfortably spray it in any direction, even upside down.  


However, you may need more than one bottle to remove thick rust or cover larger exterior surfaces such as the undercarriage or doors. Also, it has a strong odor, so consider wearing a respirator when using it.

Easiest To Apply
Permatex Rust Treatment

If you are searching for the best rust prevention spray, your search may stop when you get Permatex Rust Treatment. It has an easy application process and kills rust on all automotive applications—from trucks to hatch covers. It also removes rust on agricultural equipment but can only be used on surfaces 200-degrees Fahrenheit and lower. One of the traits that make this spray great is you can use it over rust. You will not need to apply a pre-cleaner before application. Its two main ingredients, Tannic acid, and 2-Butoxyethanol are organic extracts. When sprayed, they form a film on the rusted surface and create a good base for painting. 


But as much as it is a useful product with multiple uses, it has its drawbacks. For example, you have to give it time to completely dry. You will know it’s dry if it forms a protective coating on the sprayed area. You also need to wear the appropriate gear because it has a strong odor.

Best Rust Convertor
VHT Rust Converter

VHT's rust converter is designed to be used on rusty areas and to stop rust in its tracks. It's a clear spray that changes to a black metal protective coating to prevent additional rust from occurring. You can then sand the area for a smooth and even finish. It can be used on metal, fiberglass, and body filler and takes 24 hours to completely dry. This product does what it says it will do and converts rust into a solid form of metal. After treatment, it’s easy to paint the surface area. Overall, it adheres well, and you don’t have to do too much prep because it doesn’t affect anything that isn't rusty. Overspray does not affect the areas around it or cause any discoloring.


One downside to this product is that it runs out quickly because it comes in small cans, so you may need more than one can to complete a project. Also, the nozzle tends to clog.

Honorable Mention
3M Professional Grade Rubberized Undercoating

The 3M undercoating spray is one of the best undercarriage rust protection sprays for cars and trucks. One reason is that it doesn't run or sag during and after application. We also love its stand-out noise deadening feature. It is asphalt-based, something that makes it perfect for road noise control. This pack contains six 16-ounce cans. Two of the cans are enough to cover an entire underbody, and you can store the extra ones for future use. The rust prevention spray leaves a black, glossy finish that makes your undercarriage less vulnerable to corrosion and abrasion. 


The 3M undercoating is a handy product you can use on most parts of your car. But as a precautionary measure, make sure you treat the rusted areas first. Applying it over rust can trap water and cause rust to damage your car parts from the inside. The application angle is also crucial. It will dissolve if you don’t hold it at a semi-flat angle.
Honorable Mention
CRC Heavy Duty Corrosion Inhibitor

This corrosion inhibitor is for use on metal surfaces, engine parts, fasteners, and electrical connections. It provides good protection on steering and throttle linkages, spindles, motors, shafts, and more. This product makes its way into cracks, seams, and rust, and thickens over time. While it doesn't reverse rust damage, it can stop it from spreading. It sprays evenly, lightly, and dries to a hard waxy compound. Overall, it works well to protect against saltwater, corrosion, rust, and damage.


However, the nozzle makes it challenging to use in hard-to-reach places. Also, it may leave behind a light yellow color on the surface area, which is not very attractive.

Honorable Mention
STA-BIL Rust Stopper

If you notice rust forming in the hard-to-reach areas of your vehicle, then you can use STA-BIL’s Rust Stopper to penetrate those surfaces. This is because the solution is packaged in a 13-ounce spray can that’s designed with an elongated spray nozzle that helps direct the solution in the tight spaces. It’s a water-resistant formula that leaves a long-lasting film on exposed metal surfaces to prevent rust and corrosion. The film also resists thinning even when exposed to adverse weather conditions. It also contains lubricative agents so it can be used to stop squeaks or jamming of bolts, joints, and the exposed moving parts of your vehicle. It can also be used in other applications including motorcycles, bicycles, farm and marine equipment. 


However, some users have noted that the product remains sticky for a fairly long time so you may not want to use it on parts that you handle regularly such as the door.

Honorable Mention
Rust Kutter

This rust converter stops the spread of rust and treats the metal so rust does not continue to form. It ships ready to use with a spray nozzle and can be used on anything, indoors and out, that rusts. It's safe for use on antique vehicles, farm equipment, tools, galvanized buildings, and more. This product is perfect to use on rusted undercarriage or suspension components. It sprays easily and covers the surface area well. If you want to make rust inert and prevent it from spreading, this stuff does the trick. Some users have even reported that the product removes thick layers of rust.


Be aware that if you get this on your skin, it might cause some irritation. Also, you should wear safety glasses and use it in a ventilated area as it has a strong odor. It also leaves behind a white residue.

Tips

  • When using rust inhibitors, it is vital to know which ones require prior preparation of the rusty parts. Not all sprays can be used directly on rust. Some work as preventers while others work as treatments.
  • Be sure to check whether your rust prevention spray can be used with paint. Although the sprays leave a clean finish, painting over the surface afterward might be ineffective. Also, confirm whether it's safe for bodywork. 
  • Always wear the right gear. Rust preventers for cars can have a strong odor that may overwhelm you. A pair of gloves and a nose cover may be very useful. 
  • Make sure you get extra cans. This will ensure you cover every part, and you can store any additional products for future applications. 
  • If you aren’t sure of the effect, test the spray on a small area first. 
  • Depending on the car part, you can choose the most effective application method. Spraying is the top technique, as the formula gets to all the nooks and crannies. However, there are situations when you may need to consider applying the formula using a cloth. 

FAQs

Q: Which is the best rust prevention product?

While all the rust prevention sprays featured on our review are some of the best on the market, we rate BOESHIELD T-9 Rust & Corrosion Inhibitor highly for its high-grade rust prevention, anti-corrosion, and lubricative properties.  

Q: Can these rust removers be used on household products?

Anti-corrosion sprays for cars have harsh chemicals that might not be suitable for food-grade household items. You can use products such as Evapo-Rust Super Safe Rust Remover to clean household items. DIY home remedies for rust removal — such as vinegar, baking soda, and acetic acid — also work well.

Q: What’s the difference between rustproofing and undercoating?

Rustproofing involves applying a rust inhibitor on any surface of the vehicle that may be prone to rust. In contrast, undercoating involves applying a sealant coat on your car’s undercarriage to protect it from rust, corrosion, or minor scratches. 

Q: What is a rust inhibitor? 

A rust inhibitor or a rust stopper is a chemical that slows down the oxidation process that causes rust. It seals the surface with a long-lasting coating that locks out moisture and oxygen, both of which are necessary for rust formation.  

Q: Can rust inhibitors be applied to areas that get hot, such as exhaust pipes?

Unless stated otherwise, manufacturers do not advise applying these sprays on areas that exceed 200 degrees Fahrenheit (93 degrees Celsius). 

Final Thoughts

We found the BOESHIELD T-9 Rust & Corrosion Inhibitor to be the best rust prevention spray for most vehicles. It utilizes anti-corrosion and waterproofing technology to provide effective rust protection. If you only need a budget-friendly rust remover to remove small traces of rust on your vehicle’s body, then you can use the Rust-Oleum Rust Reformer Spray.