LAST UPDATED: September 22, 2020

The Best Rust Prevention Spray for Cars (Review) in 2021

Best Choice BOESHIELD T-9 Rust & Corrosion Protection/Inhibitor BOESHIELD T-9 Rust & Corrosion Protection/Inhibitor
Premium Pick Corroseal Water-Based Rust Converter Metal Primer Corroseal Water-Based Rust Converter Metal Primer
Best Value Permatex 81849 Rust Treatment Permatex 81849 Rust Treatment
Rust is a problem for many car owners, and it can damage many of your vehicle’s components, including the body, engine, and electrical equipment. It’s vital that you control it and remove it when necessary. Fortunately, there are plenty of anti-rust solutions available, including rust prevention sprays. These simple but effective products create a protective film that prevents metal from rusting. There’s no time like the present to increase the protection of your car or truck. We’ve scoured the web for the best rust prevention sprays around and answered some common rust-related questions that drivers have. Now, you can keep your car rust-free, regardless of the season. So let’s go ahead and take a look at some of the best rust prevention sprays on the market right now.

The Best Rust Prevention Spray for Cars

Boeshield’s anti-corrosion spray was developed by the Boeing Company to lubricate and protect aircraft components. It combines anti-corrosion technology with waterproofing and lubrication. Boeshield’s T-9 solution loosens rusted and corroded parts while displacing dirt and old lubricants and works its way into moving parts for better lubrication. It dries to a thin, waxy layer that clings to the metal and protects it for months.

Boeshield’s T-9 formula is safe to use on any metal surface, as well as paints, plastics, and vinyl. This makes it diverse enough for use with everything from bicycles to cars, to tools. It’s also a cost-effective way to give your car the protection it needs.

Key Features
  • Easy-to-apply anti-corrosion spray developed to aircraft standard
  • Provides rust protection, lubrication, and waterproofing
  • Loosens existing rust
  • Displaces dirt and existing lubricant
  • Dries to a thin, waxy layer, which lasts for months
  • Suitable for use on exposed metal, painted metal, plastics, and vinyl
  • Brand Boeshield
  • Model 122182
  • Weight 15.8 oz

Corroseal tackles rust with its all-in-one rust converter, primer, and paint. The liquid is formulated to restore and extend the life of metal surfaces with ease by converting rust into chemically stable iron tannate. Non-flammable and non-corrosive, the solution is suitable for automotive, household, and even marine applications.

Another useful feature of Corroseal’s rust-prevention solution is the fact that its water-based formula is easy to clean with soap and water. In addition, it’s simple to apply using whatever method suits you best, such as by brush, roller, or spray. Users report that this product works wonders converting rust.

Key Features
  • All-in-one rust prevention, primer, and paint solution
  • Extends the life of metal surfaces
  • For automotive, marine, and household purpose
  • Easy to apply
  • Water-based solution is easy to clean up with soap and water
  • Brand Corroseal
  • Model 82331
  • Weight 9.85 lbs

3M is known for its high-quality automotive products, and this rust undercoating spray is no exception. Available in both rubberized and non-rubberized options, the unique, asphalt-based formula dries to a black protective coating that effectively protects against corrosion. 

The no-run solution makes it easy to apply, whether you’re protecting a car, truck, or recreational vehicle.  The coating is also easy to apply due to its built-in aerosol dispenser. Another great feature of this spray is that, when you apply it correctly, the layer of rust protection also acts to absorb and deaden road noise.

Key Features
  • Professional standard undercoating protects against corrosion and abrasion
  • Perfect for undercarriages, wheel wells, floor pans, and more
  • The asphalt-based formula also helps deaden road noise
  • Easy to apply thanks to its aerosol dispenser
  • Suitable for cars, trucks, and recreational vehicles
  • Brand 3M
  • Model 03584
  • Weight 1 lb

Fluid Film’s rust prevention spray does exactly what it says on the can. Although it won’t remove existing rust, users report that it can keep rust away from virtually anything. Made from a natural, lanolin oil-based formula, Fluid Film’s rust treatment has the added benefit of being totally non-toxic, making it easier to apply without the need to wear a mask.

Manufactured to the highest quality in the United States, the unique formula sticks around so well that most users report only needing to apply the film once each year just before winter arrives.

Key Features
  • High quality rust inhibitor (does not tackle existing rust)
  • Manufactured in the US
  • Keeps rust at bay for up to a year
  • Suitable for virtually any metal component
  • Natural lanolin oil formula means the spray is non-toxic
  • Brand Fluid Film
  • Model Lubricant/Corrosion Inhibitor
  • Weight 11.7 oz

When CRC says “heavy-duty,” it means it. This corrosion inhibitor provides a tough but flexible coating that’s suitable for a huge range of metal components. The spray is easy to apply, and its carefully blended formula is designed to creep into every nook and cranny before firming up to provide a durable layer of protection.

Suitable for marine use as well as automotive applications, CRC’s rust-proofing solution will hold its own even in wet, salty conditions. CRC recommends using its product on everything from electrical connections to engine components and trailers. Users report that this spray provides a thinner, more even coating than many of its competitors.

Key Features
  • ‘Heavy-duty’ rust proofing holds up even in marine conditions
  • Provides a tough but flexible coating on any exposed metal
  • Easy to apply
  • Offers a more even coating than many options on the market
  • Long-lasting effects
  • Brand CRC
  • Model 06026
  • Weight 1.44 oz

VHT’s rust remover for cars is a powerhouse when it comes to fixing rust problems. When sprayed directly onto metal, rusted areas are destroyed on contact, leaving behind an even black coating that also acts to prevent more rust forming in the future. The formula can be safely applied not only to metal but also to body filler and fiberglass, making it one of the most diverse options on the market.

A number of people have used this product to salvage metal that would otherwise have gone to the scrap heap, making it a great option for thrifty hobbyists. You can paint over the tough film that the product forms following 24 hours of drying time, so you don’t need to sacrifice the appearance of your equipment to get the most out of this product.

Key Features
  • Rust converter and preventer that can be sprayed directly onto rusted areas
  • Suitable for use on metal, body filler, and fiberglass
  • Easy to use spray-on application
  • Great for salvaging equipment that might otherwise have to be scrapped
  • Dry in 24 hours
  • New rust-proof surface can be easily painted over
  • Brand VHT
  • Model SP229
  • Weight 14.2 oz

With the ability to be painted directly onto rusted surfaces, POR-15’s rust stop is a versatile solution suitable for virtually all metal surfaces. The formula easily dries to a highly flexible and shatterproof layer, which prevents further rust from forming. Users report that the formula really grips to rust and is easy to apply, making it ideal for the underside of any vehicle.

Because the coating easily spreads out to a thin and even layer, it also goes a lot further than you might expect. With just an inexpensive bristle brush, whole vehicle undersides can be covered with a single can. POR-15’s tough car undercoating solution is guaranteed to keep the threat of rust at bay for months – or even years.

Key Features
  • Rust solution that rectifies existing rust as well as preventing future formation
  • Suitable for most metal surfaces
  • Particularly recommended as a truck undercoating
  • Long-lasting rust prevention
  • Easy to apply with an inexpensive bristle brush
  • Brand POR-15
  • Model 45404
  • Weight 2.4 lbs

Rust Bullet’s rust inhibitor paint is a two-in-one solution that not only kills rust but also prevents it from coming back to haunt you. Its rust paint is the only one on the market with a patent, proving that it’s unique in its class. The formula is a little thinner than many of its competitors, making application via spray, roller, or brush quite easy. The result is a smooth layer that stands up against chips and scratches.

Another unique feature of the formula is its UV resistance: powerful radiation from the sun won’t damage the coating. This makes it the perfect option for use in all climates, whether you need to protect your car from snow and salted roads or the blazing sun. Finally, this rust proofing paint is versatile enough for use as both a stand-alone protective coating or on already-painted surfaces.

Key Features
  • Two-in-one rust solution that converts existing rust and prevents further rust from forming
  • Patented
  • Thinner formula for easy application via spray, brush, or roller
  • Scratch and chip resistant
  • Resistant to UV radiation
  • Brand Rust Bullet
  • Model 8.56084E+11
  • Weight 2.7 lbs

Permatex’s solution is a true rust killer, dissolving rusty spots in mere minutes and leaving behind a durable polymer coating. Easy to apply by brush or spray, the coating makes an excellent rust-proof primer that can be easily painted over to ensure a durable finish.

The formula is suitable to use with body filler and fiberglass as well as metal, making it a diverse solution for most automotive surfaces. Users report that Permatex’s formula is highly effective and easy to apply, making it a handy bottle to keep on hand around the garage.

Key Features
  • Dissolves rusted spots in a matter or minutes
  • Suitable for use with metal surfaces, body filler, and fiberglass
  • Easy to apply
  • Can be used as a primer and painted over
  • Leaves behind a durable black surface that’s resistant to rusting
  • Brand Permatex
  • Model 81849
  • Weight 14.4 oz

Another way to stop rust on vehicles is to apply a little bit of Rust-Oleum’s rust reformer. The solution instantly converts rust to an inert surface that can then be painted over for a smooth and durable finish that resists the formation of rust in the future.

In its cleverly designed bottle, the solution can be sprayed at any angle, making it easy and comfortable to apply no matter what part of your vehicle needs to be treated. Users agree that Rust-Oleum’s formula is a simple and effective way to tackle rust wherever it forms.

Key Features
  • Rust reformer converts existing rust to a protected, easy-to-paint surface
  • Prevents more rust from forming in the future
  • Easy to apply as a spray from any angle
  • Great solution for salvaging rusty metal parts that might otherwise be abandoned
  • Brand Rust-Oleum
  • Model 248659
  • Weight 12 oz

Best Rust Prevention Spray Buying Guide

That concludes our list of the top 10 rust prevention solutions on the market right now. Clearly, there are plenty of options to choose from, each of which can carry out different functions! With this in mind, it should come as no surprise that deciding on exactly the right solution for your needs can be a challenging task. That’s why we’ve compiled a list of common questions and concerns people have when diving into the world of rust prevention. We hope the following information will help you come to an informed decision.

What to Consider When Buying a Rust Prevention Spray

Below we work our way through some of the most important factors to bear in mind when choosing your rust prevention spray:

  • The Surface to be treated

When choosing a rust prevention treatment, one of the first things to check up on is what type of surface the product is suitable for use with. Plenty of rust prevention and vehicle undercoating solutions are suitable for use on fiberglass and body filler as well as metals, but this is not always the case. Be sure to check the manufacturer’s advice prior to purchase.

  • Removal or Prevention

Another key factor that will influence your decision is whether you want to deal with existing rust, or simply prevent it from forming in the future. Solutions that remove rust as well as preventing its formation effectively allow you to paint over rust. Most of the solutions on this list perform both functions, but it’s always a good idea to double check.

  • To paint or not to paint

If you are planning to treat a visible surface, make sure you choose a rust inhibitor that can also act as a primer, so you can easily paint over it. Bear in mind that products designed to convert existing rust tend to leave a dark brown or black surface behind, so you will probably need to apply at least two or three layers of paint to adequately cover it.

  • Application

If you dislike the idea of working your way over multiple uneven surfaces with a wire brush, you may wish to choose a rust inhibitor that can be applied via spraying. Most can be, but if you do not have your own spraying equipment, it could be worth selecting a formula that comes in a spray can as standard paint over rust.

Related Posts: Best Car Paint, Spray Paint For Rims and Automotive Touch Up Paint

rust prevention spray

Why Should You Use a Rust Inhibitor?

Rust proofing cars are one of the single best ways to keep vehicles in the best possible condition. Corroded components are more likely to fail over time, and could be costly and difficult to fix. Because of this, rust proofing your car is a small investment that makes for huge benefits further down the road (pun not intended). Below are just a few of the many benefits you can expect from using a rust-proofing treatment on your vehicle:

  • Ensuring a vehicle is adequately treated for rust increases its resale value
  • Repairing rust damage is a costly and time-consuming endeavor, which can be avoided by preventative rust-proofing
  • Over time, rusting compromises how well your car’s components perform – because of this, applying a rust prevention treatment improves its overall safety
  • Stopping rust before it starts is a simple way to significantly increase the lifespan of your car

Different Types of Car Undercoating

Before paint is applied, car bodies are typically treated with what is known as an undercoating, which is designed to protect the vehicle against damage. Although undercoatings are often imbued with anti-corrosion properties, it’s worth remembering that rust-proofing and undercoating are actually two different treatments.

Below are a few key types of car undercoatings to be aware of:

  • Rubberized

Rubberized undercoatings are perhaps the most commonly used. They protect a vehicle’s undercarriage against dust, moisture, and dents, as well as helping to reduce road noise.

  • Polyurethane

This polymer coating tends to be quicker and easier to apply than its rubberized counterpart. The undercoating seeps into any cracks and seams, and bonds with non-rusty areas to protect it against corrosion.

  • Wax or Paraffin

Wax or paraffin is the quickest, cheapest type of undercoating you can apply — however, it tends to wear off more quickly than other options, typically needing to be replaced every year.

  • Asphalt

Asphalt-based coatings tend to be used on large trucks and heavy machinery, as it provides extra protection against flying debris and moisture compared to other types of undercoating. Applying this type of undercoat is typically more time consuming, as it takes longer to cure than wax, polyurethane, or rubberized undercoatings.

Rust Proofing Spray or Paint?

As mentioned earlier, you will need to decide whether to use a spray or paint method when the time comes to rust proof your vehicle. Both methods have advantages and drawbacks, which we’ve outlined below:

Spray Application


  • Can be applied to nooks and crannies where a brush might struggle to reach
  • Can cover large areas more quickly


  • Offers a thinner layer of protection than painting would
  • Targeting particularly problematic spots is more challenging

Paint Application


  • Offers a thicker, more durable layer of protection
  • Makes it easy to target problem areas with a thicker coating of the product


  • Because of painting results in a thicker layer of rust-proofing, it will take longer to dry
  • Application with a brush is more time-consuming
  • Covering large areas with this method is challenging

For best results, we recommend treating the worst rusted areas with a brush, before spraying the overall area for a complete, yet targeted solution.

How to Prevent Rust?

As well as applying your car with a rust treatment, there are plenty of other simple steps you can take to keep your car free from rust – below are some simple yet effective tips:

  • Wash your car regularly – this ensures that any salt and dirty water that could contribute to rust is removed before it can become a problem. Ideally, a car should be washed every week in winter and every two weeks in other seasons.
  • Wax your car now and again – waxing every four to five months provides your car with an extra barrier against water and salt.
  • Store your car under a cover – Using a cover when your car is in storage keeps away salt, water, and other rust-causing substances off your car during periods of inactivity.
  • Check for rust regularly – Rust is far easier to deal with if it is caught early! Try to give your car a once-over for rust whenever you remember – it could save you considerable time and effort in the long run. On painted surfaces, look out for bubbles and blisters, as these are tell-tale signs of rust.

Related Posts: Best Car Wax and Best Portable Garages

Best Rust Prevention Spray for Cars FAQ:

Q:  What is a rust inhibitor?

A:  A rust inhibitor is a formula designed to slow down the chemical process of oxidation which results in rust. They can work in a few different ways:

  • Providing a thin protective coating to keep iron away from the oxygen in the air
  • Absorbing oxygen that could otherwise react with the metal
  • Inhibiting the chemical process of either reduction or oxidation, both of which are necessary for the formation of rust

The solutions on this list work by the first method.

Q:  How does corrosion take place?

A:  When iron rusts, the process is a type of corrosion.

Rust is the common name given to iron oxide, which forms gradually whenever iron or an iron-based alloy is exposed to oxygen for extended periods of time. This is because iron is a relatively reactive metal, which can form chemical bonds with a number of elements.

Q:  How do I apply an undercoating?

A:  Applying a rust-proof undercoating at home is a relatively straightforward endeavor, which most keen automotive DIY enthusiasts can undertake. You’ll usually carry out the following steps:

  • Prepare your work area – this should be clean, well-ventilated, and adequately lit. It’s also a good idea to wear a dust mask or ventilator and work on a day with low humidity to ensure the coating dries as quickly as possible.
  • Prepare the surface – what this means will vary depending on what you are trying to rust-proof. For a whole car body, you’ll usually need to strip the existing paint away to apply a rust-proof undercoating, whereas to treat the undercarriage will usually mean a simple wash.
  • Remove any existing rust – rust can usually be sanded down to provide a better surface for applying whichever solution you have chosen.
  • Tackle problem areas first – when dealing with a surface that has already rusted, apply your treatment with a wire brush to the worst-affected areas first.
  • Give the surface an overall spray – next, use a spray gun (or can) to coat the surface with an even layer of the formula.
  • Dry – how long the drying process will take depends upon the rust prevention solution you have selected, but bear in mind that the thicker the layer you apply, the longer you can expect it to take.
  • Paint if necessary – Finally, if you applied the solution as an undercoating, now is the time to cover it with a fresh layer of paint. You may need to apply several layers in order to hide the undercoating, as rust converters tend to produce dark brown or black surfaces.

rusty wheel

Our Top Pick

Our pick for the best rust prevention spray for cars is Boeshield’s all-in-one anti-corrosion spray. It’s a high-quality product that was developed for use with Boeing aircraft, so you know it’s good. In just one step, the spray dissolves minor rusted areas, displaces dirt and grime, provides lubrication for moving parts, and dries to a tough yet flexible anti-rust coating.

Since the formula is available in a spray can, it’s also really easy to apply, regardless of whether you are treating exposed metal, painted metal, plastics, or even vinyl. Overall, this is a cost-effective and simple solution that’s designed to last.


  1. 6 Ways to protect your Car or Truck from Rust this winter – Best Ride
  2. How Rust Inhibitors work – Cars Direct
  3. Is Rustproofing Your Car a Good Idea? – Your Mechanic