The Best Rust Prevention For Cars

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Rustproofing your car is an essential task to ensure that it’s protected during the winter season with all the salt and other harmful elements on the road. Rust prevention spray or paint is the best method for protection and is very simple to apply.

The best rust prevention paint for cars is the POR-15 45404 Anti Rust Paint, which provides a strong heavy duty protection against rust getting through.

Modern cars are less prone to rusting due to their age and technological advances in paints and galvanized bodywork providing maximum rust prevention. However, overtime rust will appear on any car that is used daily on salty roads.


Rust Proofing Spray and Paint Comparison


Common places for cars to rust are the fenders, front valance, near headlights, sills, floorpans, tailgate, sub frame, jacking points and more. Ensuring these areas are covered with rust prevention spray will further extend their life span.

Before applying any rust prevention paint or spray, rust must be removed beforehand. The best method of removing rust from the underneath of the car is by using a wire brush or an attachment on a drill. This will remove all the loose rust, which means you can begin to paint over it with rust preventive spray paint.

Below is a list of the best rust prevention sprays and paints that tackle rust and ensure that it’s protected against salt and other elements.

The Best Rust Prevention Paint and Spray

1. POR-15 45404 Rust Prevention Paint

POR 15 stands for “Paint Over Rust” and it’s one of the strongest rust prevention paints you can buy. The brand also states that you don’t even need to remove rust prior to applying the formula but we recommend that you do for the best results.

There is no spraying or heating up of this product, it’s as simple as dipping the paint brush into the pot and applying to the work surface. It creates an air tight seal rust free barrier that no rust can get through. It also provides a non-porous coating that wont chip, crack or peel.

Other features of the POR-15 Rust Preventive Paint include:

  • Seals rust permanently
  • Lead free formula
  • Protects against further exposure to moisture
  • Non shattering and highly flexible
  • Available in 1 pint, 1 gallon or 1 quart bottles
  • Choice of colors (clear, gray, silver or gloss black)
  • Award winning anti rust paint
  • Professional grade

The POR-15 formula is the best rust prevention paint available that provides a heavy duty coating that protects from all harmful elements.

When applying this product, we highly recommend using cheap paint brushes as they will be unusable once POR-15 dries on the bristles of the brush. We use this product in our buying guide below if you want to see how its applied.


2. KBS Coatings 4401 Rust Seal For Cars

Rust Seal by KBS Coatings is a rust prevention paint that permanently seals corrosion and can be used in the auto, marine or industrial industries. It’s very similar to the POR-15 above but has many more colors options to choose from.

There is no other rust prevention paint on the market that offers as many color options as the Rust Seal by KBS Coatings. This means you are able to paint a range of different auto parts such as truck bed liners, areas of the chassis and more.

Other features of the KBS Coatings 4401 Rust Seal include:

  • Available in 10 different color options
  • Permanently seals the surface
  • 1 gallon, 5 gallon, 1 pint, 1 quart, 8 ounces bottle sizes
  • Resistant to cracks, chips or scratches
  • Locks out water and air
  • Can withstand temperatures up to 600 degrees

It’s one of the best auto rustproofing formulas that provides a durable protective layer over exposed areas that suffer from corrosion. POR-15 may be more superior but the Rust Seal provides better value for the money and far more color options.


3. Rust-Oleum Stops Anti Rust Paint

The Rust-Oleum is one of the most popular aerosol types of rust prevention spray due to its low cost and superior coverage. The brand also offer the spray in over 30 different colors options for those that prefer certain colors on their underbody.

Unlike other aerosol rust prevention spray alternatives, this formula is designed to provide a flat finish, which minimizes surface imperfections.

Other features of the Rust-Oleum Protective Enamel include:

  • Weather and corrosion resistant coating
  • Oil based formula
  • Dry to touch in 2 to 4 hours
  • Cover up to 15 square feet
  • Easy application via aerosol
  • Chip resistant
  • VOC compliant

It’s a low cost solution to preventing rust from spreading on your car. As its an aerosol, there is no need to purchase paint brushes or a spray can. It’s as simple as spraying it into the rust and allowing it to dry appropriately before driving the vehicle.


4. 3M 03584 Rubberized Undercoating

3M is a huge brand in a range of industries and this anti rust protective coating is ideal for the underbody. It can be purchased as a rubberized or non-rubberized formula but for maximum protection, we recommend the rubberized formula.

Another benefit of using this formula is that it provides sound deadening qualities, which can make a big difference for certain vehicles.

Other features of the 3M 03584 Undercoating include:

  • No run formula for clean application
  • Additional sound deadening properties
  • Asphalt based product
  • Textured finish
  • Resistant to chipping, abrasion and scratches

It’s the best undercoating for cars that protects against rust and provides a textured matte finish. The only drawback is that you will need multiple cans to complete the job and this could be fairly expensive when compared to the alternatives.


5. Waxoyl Rust Inhibitor Spray

Waxoyl by Hammerite is a rust prevention spray that is available in a clear or black formula. Unlike the POR-15 alternative above, this formula will require heating up in order to “wake up” the rust inhibitor molecules and be easier to spray.

Correct application of Waxoyl provides excellent rustproofing capabilities and when sprayed, the liquid formula is able to reach all the nooks and crannies.

Other features of the Waxoyl Rust Inhibitor Spray include:

  • Available as a clear or black coat
  • Weatherproof wax coating finish
  • Cuts through oil, grease and dirt
  • Sprays easily between small gaps
  • Available in 1 or 5 liter bottles

It’s the best rust prevention spray that provides a durable barrier against rust and other harmful elements. The only drawback is that the application is more involving but once used with a pressure sprayer, it provides great results.


Rust Prevention Buying Guide

Whether you own a classic car or a beater car, rust can be a big problem. The underbody of your car is where the majority of the rust will occur and you can have cars that look pristine bodywork wise but can have holes in the floor.

From a classic car point of view, you will want to ensure that everything is protected in order to increase the resale value. Those that drive beater/average day cars will want to ensure rust doesn’t spread and that they can keep the car on the road for as long as possible and pass inspections.

In general, car rust is caused by metal being exposed to iron, oxygen or water where the reaction oxidizes the metal. This process can be caused by the following:

  • Mud building up in inaccessible areas such as a wheel arch lips
  • Stone chips or minor damage
  • Driving regularly on salty roads during winter
  • Living near the sea (high moisture and salt)
  • Blocked car drain holes

rustproofing POR-15

Rust Prevention Spray or Paint?

Within this article, we have mentioned a list of rust prevention sprays and paints. This is because they both provide different benefits. For example, using a rust prevention paint will provide a more durable protective layer and its generally more heavy duty. However, using a rust prevention spray allows you to spray into places where a paint brush will not reach and spray a larger area far quicker.

When performing auto rust proofing on cars, we recommend that you use a paint on the worst effected areas and then spray the whole area afterwards for all round protection. We discuss this is more detail below.

Application of Rustproofing

When you have purchased your anti rust paint or spray, you are now ready to begin rustproofing your car. However, before you begin applying any paint or spray, you should clear the surface beforehand. We recommend that you use a pressure washer to remove tough dirt on the underbody. You can then use a wire brush attachment to clear any dirt left over and remove any corrosion that is present. Although some paints say you are able to paint over rust, it is worthwhile removing it for the best possible result.

Its vital that no dirt or moisture is left as this will become trapped and cause rust itself. Take a look at some of the best rust converters that bond with rust and form a polymer compound. Once complete, you are ready to begin rustproofing.

Personally, using a mixture of both a paint and spray such as POR-15 and Waxoyl is the best route and as you can see below, we used the silver POR-15 on the worst rust areas to begin with.

Once that has dried, simply spray the spray of your choice at all of the underbody of the car (see main article photo). Be careful not to spray major components such as the brake caliper and pads as this may cause issues.

This method of rust prevention has deemed very successful over the years with various of my personal cars. Regularly repeating this process of auto rustproofing over the years will ensure your car does not suffer bad corrosion that will effect its resale value. It is a messy process but worth doing because rust that is not treated will take its toll on your vehicle.


Durability of the auto rustproofing that you use is crucial to the effectiveness. If it is not weatherproof, chip and scratch resistant, it will not be very durable considering that its applied on the underbody of the car.

Using a rust preventive paint instead of a spray is usually a more durable method. However, it can be more time consuming to apply in large work areas and you will not be able to get into all the small gaps. Therefore, apply paint in the areas that are mostly effected by corrosion and then use spray for everywhere else.

How to Avoid Corrosion?

Road salt is one of the main reasons for car rust and its mostly during the winter season. For those with only one vehicle to drive, driving in the winter season with salt spread across the road is inevitable.

For those winter months, its vital that you thoroughly wash your car and paying special attention to the underbody and washing all four arches excessively. With the build up of salty and dirty roads, be sure to check that the drain holes are all clear and water can run through.

Stone chips and damage from driving is also hard to avoid in everyday driving. Using the correct protective car wax for your paintwork will provide an excellent source for prevent stone chips and repelling road dirt from your cars bodywork.

However, the best tactic for avoiding rust on your car is by applying rustproofing products as recommended above. This prevents the car metal getting in contact with any dirt or water that will cause the rust process.


Luckily, car rust is far less common than it was pre 1980’s with some cars starting to rust just a few years after being driven out of the factory. However, for those that are keeping classics and generally older cars on the road, protecting the underbody is crucial.

All of our recommendations do a great job at preventing rust and we highly recommend using both a paint and a spray for maximum protection.

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