Don't Waste Your Money is supported by our readers. When you purchase an item through links on our site, we may earn an affiliate commission.

The Best Rust Prevention Sprays For Cars - 2021

Last updated on June 22, 2021
Best Rust Prevention Sprays For Cars

Why Trust The DWYM Score?

DWYM is focused on helping you make the best purchasing decision. Our team of experts spends hundreds of hours analyzing, testing, and researching products so you don't have to.Learn more.

Look for the DWYM seal for products that are the best in a category.

Our Picks For The Top Rust Prevention Sprays For Cars

Show Contents
Our Take
  Best Overall

Cosmoline RP-342 Heavy Rust Preventative Spray, 3-Pack

Don't Waste Your Money Seal of Approval

Cosmoline

RP-342 Heavy Rust Preventative Spray, 3-Pack

Overall Take

One of the OriginalsThis is a popular spray that has been around for many years as a trusted rust-prevention technique.

  Best Value

Fluid Film Aerosol 11.75-Ounce Rust & Corrosion Protection, 6-Pack

Fluid Film

Aerosol 11.75-Ounce Rust & Corrosion Protection, 6-Pack

Overall Take

Powerful FormulaThis rust prevention spray won't crack or freeze, which means you can use it in the cold winter months.

  We Also Like

VHT SP229 Black Rust Convertor Spray Can, 10.25 Ounce

VHT

SP229 Black Rust Convertor Spray Can, 10.25 Ounce

Overall Take

Neutralizes on ContactInstantly improve the look of your vehicle with this rust convertor spray.

  Easy and Effective

WD40 300035 Specialist Corrosion Inhibitor Spray, 6.5-Ounce

WD40

300035 Specialist Corrosion Inhibitor Spray, 6.5-Ounce

Overall Take

Fights Rust and MoreThis anti-rust and anti-corrosion spray and is easy to use and effective.

Guide written by Danielle Smyth
Last updated on June 22, 2021

Nothing ruins a car faster than rust. Once you find it, the problem can be too far gone to repair. Though auto manufacturers use modern materials and test and treat them, vehicles are still vulnerable to rust.

There are three main types of rust prevention car sprays: tar-based, drip oil and dripless. Tar-based sprays, also known as undercoating, are sprayed onto the exposed parts in the car’s underbody, and in wheel wells and floor pans. These form strong shields, but they can crack.

Drip oil sprays are applied through holes that are first drilled into the vehicle’s body. This is the most common kind of car rust-proofing, but it needs to be done once a year.

The third type, dripless oil sprays, are more similar to tar-based ones. These also harden after you spray them on. As with drip sprays, though, holes still need to be drilled in the vehicle before applying.

Car owners can pay for rust prevention services when purchasing their vehicles. This may already be included in the initial purchase cost. Rust proofing can also be done at a body shop, and can cost anywhere from $125 to $150. Another option is to buy the spray and do it yourself. Most can make wide or narrow sprays, because they come with interchangeable nozzles. Some leave sticky films, while others dry faster, but all are cheaper than taking a car to the shop.

Rust conversion sprays are different, and are used on existing rust. These aerosol sprays convert rust into black coatings, which can then be primed and painted with oil-based top coats. Read the instructions carefully, as you may also have to sand the finish after the spray is applied.

The Best Rust Prevention Sprays For Cars

1
  Best Overall

Cosmoline RP-342 Heavy Rust Preventative Spray, 3-Pack

This reliable rust prevention spray has been used by the U.S. Armed Forces, commercial companies and consumers since World War II. This newer formula dries faster and last longer than ever, and the coating will never crack, wash off, run off or blister.

Features


Specifications

Brand
Cosmoline
Model
2
  Best Value

Fluid Film Aerosol 11.75-Ounce Rust & Corrosion Protection, 6-Pack

No matter what type of metal you're working with, you'll want to use this rust prevention spray to keep it corrosion-free. The aerosol can makes the spray easy to distribute, even if you're working with something as large as an automobile or a boat. As an added bonus, this formula also doubles as a lubricant.

Features


Specifications

Brand
Fluid Film
Model
3
  We Also Like

VHT SP229 Black Rust Convertor Spray Can, 10.25 Ounce

This rust prevention spray goes on completely clear and then turns into a black metal. It also prevents future rust from forming on rocker panels and other metal surfaces, and can be sanded down for a smooth, even finish.

Features


Specifications

Brand
VHT
Model
4
  Easy and Effective

WD40 300035 Specialist Corrosion Inhibitor Spray, 6.5-Ounce

This “Specialist” corrosion inhibitor has a long-lasting formula that shields your metals for up to one year outdoors and two years inside. It is compliant with government VOC (volatile organic compounds) regulations in 50 states.

Features


Specifications

Brand
WD40
Model
5
  Also Consider

STA-BIL Rust Stopper And Corrosion Inhibitor Spray, 13-Ounce

This rust stopper is a spray-on coating that will protect exposed metal surfaces from rust and corrosion. It can stop existing rust from spreading, can lubricate auto parts and tools and is water resistant.

Features


Specifications

Brand
STA-BIL
Model

Our Rust Prevention Spray For Cars Buying Guide

Nothing ruins a car faster than rust. Once you find it, the problem can be too far gone to repair. Though auto manufacturers use modern materials and test and treat them, vehicles are still vulnerable to rust.

There are three main types of rust prevention car sprays: tar-based, drip oil and dripless. Tar-based sprays, also known as undercoating, are sprayed onto the exposed parts in the car’s underbody, and in wheel wells and floor pans. These form strong shields, but they can crack.

Drip oil sprays are applied through holes that are first drilled into the vehicle’s body. This is the most common kind of car rust-proofing, but it needs to be done once a year.

The third type, dripless oil sprays, are more similar to tar-based ones. These also harden after you spray them on. As with drip sprays, though, holes still need to be drilled in the vehicle before applying.

Car owners can pay for rust prevention services when purchasing their vehicles. This may already be included in the initial purchase cost. Rust proofing can also be done at a body shop, and can cost anywhere from $125 to $150. Another option is to buy the spray and do it yourself. Most can make wide or narrow sprays, because they come with interchangeable nozzles. Some leave sticky films, while others dry faster, but all are cheaper than taking a car to the shop.

Rust conversion sprays are different, and are used on existing rust. These aerosol sprays convert rust into black coatings, which can then be primed and painted with oil-based top coats. Read the instructions carefully, as you may also have to sand the finish after the spray is applied.

DWYM Fun Fact

The words “rust” and “corrosion” are often used interchangeably, and the process starts when water and oxygen meet on the metal surface. That said, they aren’t the same process.

Rust develops slowly, but it does spread consistently when not checked. As a matter of fact, any piece of iron will turn completely into rust if it is not protected. In most cases, rust prevention is more a fight to slow its spread rather than an attempt to stop it completely.

The Rust Prevention Spray For Cars Tips and Advice

  • Since tar-based sprays can crack, the vehicles should be inspected at least once a year.
  • Drip oil sprays can be messy, so you may not want to apply them when the vehicle is in the driveway, otherwise you may see oil stains.
  • If using rust converter spray, first remove the loose rust with a wire brush. You don’t want to paint over that.

About The Author

Danielle Smyth 

Danielle Smyth is a writer and content marketing expert based in New York. She has been writing on business and finance, home and garden, DIY, travel and tourism, and a variety of other topics for over a decade, and she holds a Master of Science in Publishing from Pace University. Danielle loves working on product reviews and helping others find the highest quality items and the best values. An avid gardener and home improvement fanatic, she is always looking for new products to make life easier.