What is Undercoating for Cars? Pros, Cons and How it Works (2023)

Automotive>Maintenance & Repair

March 11, 2023

Each year, American drivers spend more than $3 billion repairing rust damage on their vehicles. The damage is often worst for drivers who live in cold, snowy climates.

Road salt used to fight snow and ice does collateral damage to vehicles, causing rust and corrosion that not only leave your vehicle looking shabby but also make it unsafe.

Undercoating for cars offers a solution that can help keep rust at bay. Continue reading to learn more about the types of undercoating for cars, how much it costs, how often to undercoat your car, and more.

What is Undercoating for Cars? Pros, Cons and How it Works (1)

(Video) This is Why You NEVER Want to Use Rubberized Undercoatings!

What is Undercoating for a Car?

Undercoating for a car is a protective layer that's sprayed all over the undercarriage of your vehicle. This provides a rust-proof layer between exposed metal and salt, dirt and grime from the road. Since the undercoating protects metal from moisture and air, no rust can form.

Does Your Car Need Undercoating?

As a car owner, you probably think a lot about keeping your car in good condition, whether by following car care tips or detailing the interior regularly. But your vehicle's undercarriage might be out of sight, out of mind.

Yet, the underneath of your vehicle needs care and maintenance too. The undercarriage is exposed to dirt and road debris. That can trap moisture and oxygen, which leads to rust, which can form on exposed metal. The undercarriage is also close to road salt and road treatments that can accelerate corrosion.

Undercoating offers a measure of protection against these elements. That means you may be able to spend less on repairs and paint retouching, and maintain your vehicle's value over time.

That being said, car manufacturers now use more rust-resistant materials, like aluminum or plastic, rather than traditional steel, which rusts more easily. Since today's cars have built-in corrosion protection, you may decide that this extra treatment is unnecessary.

Undercoating vs. Rust Proofing

Rust is incredibly damaging to vehicles, so it's no surprise there's a variety of ways to combat corrosion. But there are two main aftermarket approaches that can help keep rust at bay.

  • Rust proofing: Rust proofing, also called rust protection, involves protecting specific rust-prone areas of the vehicle by applying protective wax. Rust proofing is often done on the fenders, tailgate and body panels.
  • Undercoating: This is a spray-on application that's applied to the underside of a vehicle. There are multiple options for materials used for undercoating (more on that below). Undercoating provides a more comprehensive protective layer for your vehicle.

You can choose both rust proofing and undercoating for your vehicle. But it's important to understand that these are two different treatments with different roles in protecting your vehicle from rust.

(Video) Car Undercoating Advantages and Disadvantages

Types of Undercoating for Cars

The original way to undercoat your vehicle was to spray the undercarriage with used motor oil. Luckily, we've come a long way since then. These days, there are products designed specifically for undercoating. They use the same basic method as the tried-and-true oil technique, creating a barrier between metal and the air, moisture and salt that can cause it harm.

Here are the most common types of undercoating for cars.

RubberizedThe most popular choice, a rubberized undercoating dries to a soft, rubber finish
  • Long-lasting
  • Provides sound deadening
  • Allows debris to bounce off
  • Easily removable
  • Can be painted
  • Safe for wheel wells and panels
  • Protects from some dents and dings
  • Can be tricky to apply, so you may need to pay a professional
  • Best for new, rust-free surfaces
  • Must be inspected every couple of years to ensure it's still intact
Polyurethane sealantPolyurethane sealant is sprayed on from canisters, resulting in a paint-like finish
  • Seeps into cracks, pushing out moisture and debris
  • Excellent at fighting corrosion
  • Requires time-consuming prep work, including sanding and applying primer
Wax or paraffin-basedWax or paraffin-based undercoats never entirely dry, but provide a moist barrier over exposed metal parts
  • Inexpensive
  • Easy to DIY
  • Seeps into cracks to fight corrosion
  • Will need to be reapplied at least annually
  • Can drip or rub since it never entirely dries
Oil-basedOil undercoating can be sprayed onto any surface, including one with rust, and offers widespread protection
  • Can be used on rusted surfaces
  • Penetrates rust to protect healthy metal beneath
  • Reaches inner body cavities for more protection
  • Can be DIY'ed
  • Must be reapplied annually
Asphalt-basedUsually reserved for trucks and machinery, asphalt-based undercoating is a heavy-duty option
  • Provides hearty protection
  • Reduces road noise
  • Requires professional application
  • Not paintable
  • Longer curing time
  • Only works for undercarriage

How much does undercoating for cars cost?

Undercoating can quickly get expensive, especially when you consider that this is a service you'll need again and again over the life of your car. Here's what you can expect to pay for undercoating:

  • At a dealership: $800-$1,000+
  • At an auto body shop: Up to $300
  • DIY: About $100 for cars to $150 for trucks and SUVs

While this cost can add up over time, undercoating could help spare you from more expensive rust-repair services or replacements for parts that have rusted through. The Synchrony Car CareTM credit card can be used to pay for undercoating this winter, so you can stay ahead of maintenance and begin fighting rust before it takes hold.

How long does undercoating for cars last?

If you live in a cold, snowy climate, near the ocean, or in other rust-prone areas, undercoating should be reapplied each year. Since road salt and de-icing treatments can make corrosion worse, it's best to undercoat your vehicle just before winter weather begins.

However, some undercoating options are designed to last longer. For example, rubber undercoating can last for years. Undercoating will also last longer in mild climates without snow or ice, or if you don't drive your car often.

Undercoating pros and cons

When you're deciding whether to undercoat your vehicle, ask yourself these questions:

  • Is the vehicle new or used? New vehicles are better candidates for rubberized undercoating. However, many new cars may not need undercoating, since they're built with rust-resistant materials. Since rust doesn't generally appear for five years on most cars, it might not be worth undercoating a new car that you don't plan to keep. Older cars can see more benefit from undercoating, but any existing rust will need to be removed before the undercoating is applied.
  • Do you live in a harsh climate? Road salt and de-icers commonly used in cold, snowy climates can accelerate corrosion. So can living near the salty ocean air and lots of exposure to dirt and debris. If you drive in a harsh climate or regularly take your vehicle off-roading or on dirt roads, undercoating offers an extra layer of protection that you might need.

Once you've answered those questions, it's time to weigh the pros and cons of undercoating.

  • May prevent rust
  • Some forms, like oil, can penetrate through existing rust
  • May prevent damage and extend your vehicle's life
  • May qualify you for a small insurance discount
  • Dampens road noise
  • Can be a DIY job
  • Can be costly
  • Can be time-consuming to apply
  • You must wait for the undercoating to dry.
  • Doesn't fight existing rust
  • Rust (usually) needs to be removed before undercoating is applied
  • May void your manufacturer's warranty
  • Must be reapplied regularly (every 1-3 years, depending on type)
  • Adds weight
  • Adds weight
(Video) Rubberized Undercoating Will Destroy Your Car!

Preventing Rust: More Tips

Undercoating and rust proofing aren't the only ways to protect your car from rust. In addition to considering these services, follow these steps to keep your vehicle from rusting:

  • Wash your vehicle regularly, especially in the winter months. Make sure that the undercarriage is washed too.
  • Avoiding driving during winter storms. Damaging road salt and de-icer are most concentrated immediately before, during and after storms.
  • Touch up paint and repair dents. These small places where bare metal is exposed are particularly prone to rust.
  • Give an end-of-season scrub. After winter weather is over, scrub your vehicle thoroughly.

Ready to protect your car this winter? The Synchrony Car CareTM credit card can help you pay for undercoating and other maintenance needs. No one likes a roadside emergency. Planning ahead to fight rust and keep your car running well can give you peace of mind this winter. Apply today.

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What are the disadvantages of car undercoating? ›

Cons of Undercoating

A used vehicle may already have residue on the bottom of the car or even have spots of rust and corrosion. Undercoating will not help you if corrosion already exists and the corrosion needs to be removed first before it can be applied, which can be expensive for you.

Is it a good idea to Undercoat a car? ›

Cars today are manufactured with corrosion protection, which makes this added treatment unnecessary, though it is profitable for car dealerships. Consumer Reports recommends that car buyers skip the undercoating and several other pricey add-ons, including VIN etching, fabric protection, and extended warranties.

How effective is undercoating? ›

Rubberized undercoatings do a great job of keeping existing rust all covered up and looking sharp, but it does absolutely nothing to slow down the spread of rust and corrosion sometimes the trapped air and moisture may even contribute to rust formation as was the case with GodwinAustin.

How long does undercoating last on a vehicle? ›

How long does it last? An undercoating treatment will protect you for a year. We recommend having your vehicle inspected and having a coat reapplied if necessary once a year for optimal protection.

What to avoid when undercoating? ›

Exhaust, engine: Anything that gets hot, like an exhaust pipe or the engine, should not be sprayed with undercoating. If you do accidentally spray some undercoating on these areas, just be sure not to inhale any of the fumes when they get hot. Rubber: Some undercoating products cause non-oil-resistant rubber to swell.

What type of undercoating is best? ›

Rubberized Undercoating

Overall, rubberized coating is generally the best option for protecting your vehicle's undercarriage, as it provides the simplest and best protective measures against rust and moisture.

Which is better rust proofing or undercoating? ›

Undercoating provides a more comprehensive protective layer for your vehicle. This includes the floorboards, wheel wells, and frame. Even if your car's underside isn't actually visible, it is still exposed to potential damage when you go out driving.

Will undercoating stop rust? ›

NH Oil Undercoating® will not remove rust, however it will stop existing rust from spreading by penetrating through the rust to the base metal and stopping any further oxidization. The fact is, a new vehicle is subjected to thousands of spot welds and numerous bends and folds during production.

Should you wash your car after undercoating? ›

Can I wash my vehicle after the treatment? We ask that you don't use soap and detergents on the vehicle for 48 hours after the treatment. The formula is not affected by rain, snow, or slush, just avoid washing for 2 days.

What time of year is best for undercoating? ›

Before winter kicks in, make sure to undercoat and rustproof your vehicle. The best time is summer and spring. These seasons provide a favorable environment—all much needed to maximize the treatment's effectiveness.

Do you really need undercoating? ›

The war against rust may be ultimately unwinnable, but rustproofing and undercoating can help extend your vehicle's life!. Rustproofing and undercoating can defend against the onslaught of rust-causing road salt and brine for so long. Victory requires vigilance.

What are the disadvantages of rubberized undercoating? ›

List of the Cons of a Vehicle Undercoating
  • It is less helpful if corrosion is already present. ...
  • It works best on new cars. ...
  • Most vehicles make it five years before corrosion begins to show. ...
  • A third-party undercoating service might void your vehicle's warranty. ...
  • It adds weight to the vehicle.

Do modern cars need undercoating? ›

New vehicles are better candidates for rubberized undercoating. However, many new cars may not need undercoating, since they're built with rust-resistant materials. Since rust doesn't generally appear for five years on most cars, it might not be worth undercoating a new car that you don't plan to keep.

Can you drive in rain after undercoating? ›

After you're vehicle is sprayed you can immediately drive in rain or salty snowy roads with confidence that your vehicle is already protected. You can wash it normally in a car wash or at home.

Should you wash your car before undercoating? ›

Should I Wash My Car Before Rustproofing? It's always advisable to wash your vehicle's undercarriage before bringing it for rustproofing.

What undercoating lasts the longest? ›

Woolwax® will provide the longest lasting undercarriage protection of all the undercoating products available.

What is the best way to undercoat a car? ›

1. Spray-On "Rubberized" Undercoatings. Spraying an automotive undercoating may be time consuming, expensive, and potentially dangerous, but it's your best option for keeping rust and corrosion at bay. Perhaps the most common method of undercoating a vehicle, is via the use of a "rubberized" spray-on product.

Do you have to prime before undercoating? ›

If it is a new surface, use a primer. If your painting an existing surface that has been painted before, use an undercoater. For even the most experienced professional, using the words “primer” and “undercoat” interchangeably can paint a picture of confusion.

How much does undercoating cost? ›

The general thumb rule is: On average, it can cost anywhere from $150 to $500 for a car to get an undercoat. A well-established firm that deals with car maintenance and restoration may offer a 10-year warranty for undercoating, but the cost will be from $350 to $950.

How much does Ziebart rust proofing cost? ›

Ziebart is one of the largest providers of this method of rust protection and charges approximately $150 per vehicle.

How much does Ziebart undercoating cost? ›

At Ziebart, a popular franchise that performs undercoating, charges, from we saw, was about $250 to $350, and this would include a 10-year warranty; however, in order to keep this warranty active, you would have to come back every year for about $50 per visit.

What is Ziebart undercoating? ›

Ziebart undercoating is an asphalt-based substance that's similar to tar once it's dry. It's 10 to 12 mils thick (think 20 sheets of paper) and acts as a barrier against rust and corrosion by sealing out your vehicle's underside to protect it from the harmful elements of the road.

How long does car undercoating take to dry? ›

Dry time is typically 30 minutes at room temperature. Thicker applications may take longer to dry. 5. Product can be painted after 30 minutes (best to wait 1 hour).

How long does Ziebart rust proofing last? ›

However, this wax coating typically only lasts for about a year and is, by no stretch of the imagination, a long term corrosion deterrent.

When should I undercoat my car? ›

If your vehicle has never been protected, then the best time to spray it is right now. From a corrosion point of view, the corrosion process is most active in the spring and summer months due to the increase in temperature.

What is the best way to rust proof undercarriage? ›

Another effective way to protect the undercarriage of your car is to get an oil, wax or tar-based coating. Such coatings act as a barrier and keep out rust-causing salt, moisture, and dirt. Atomized oil sprays are used widely today to undercoat the underside of most cars.

How often should you rust proof your car? ›

How often should you get rustproofing done your car? Rustproofing should be done every one to two years. Depending on your driving habits and climate, you can determine if you should go yearly or push it to two years. It may be better to consider an extended car warranty on a new vehicle purchase.

Which rust proofing is best? ›

Drip Oil Spray

This procedure is the most common and most recommended method of rust proofing, as it's able to fully rust proof your vehicle by penetrating all the small nooks and crannies.

What month is best for rust proofing? ›

The best time to have vehicle rust protection applied is definitely spring and summer. These are two periods of the year with a drier environment and when the roads are not maintained with tons of abrasives and are not constantly wet and covered with deicing salt.

What undercoating kills rust? ›

Rust-Oleum Automotive Professional-Grade Rubberized Undercoating Spray provides best-in-class protection for vehicle underbodies against minor road damage as well as rust, water, chemicals and salt.

How many cans of undercoating for a car? ›

1 Case of 12 aerosol cans is enough to properly treat the average passenger car vehicle's under-body. Wax-based undercoating technology has protected United States Military vehicles (MIL-PRF-62218B) and semi-trailer chassis components, exposed to harsh, highly corrosive environments for over 50 years.

Is dealership rust proofing worth it? ›

If you intend to keep the vehicle for a period beyond the manufacturer's rust warranty, you should consider rustproofing. Do not purchase rustproofing from a dealer. APA recommends Krown Rust Control. Please note: Most car dealers do not recommend Krown.

What does Toyota use for undercoating? ›

FLUID FILM® Undercoating is manufactured using an intricate heating and blending process, which combines unrefined wool wax with selective polar agents and corrosion inhibitors, creating a unique, lanolin-based formulation that stops existing rust on contact.

Does Ziebart rust proofing work? ›

We often get asked, “Does rust proofing really work?” and the short answer to that is yes. Ziebart's genuine rust protection is the first line of defense to protect the OEM (Original Equipment Manufacturer) integrity of your vehicle, shielding it from road salt, dirt and moisture.

Does undercoating drip? ›

NH Oil Undercoating is formulated not to drip. However, minimal dripping may occur if the product is applied heavily.

Should I rust proof my new car? ›

Rustproofing works best for new vehicles, since the sooner you can treat your car, the more protected it'll be against corrosion. But used cars can benefit, too — and that's even true if your vehicle's already starting to rust.

Does Ziebart trap moisture? ›

Does Ziebart Undercoating and Rust Protection just trap moisture? Ziebart Undercoating and Rust Protection is a barrier against moisture and oxygen. Like any barrier that sees daily abuse, over time it can eventually become compromised. If compromised, moisture can get trapped.

Why do cars not rust anymore? ›

Most modern cars are painted with a primer and sealer before final painting, reducing contact between the metal body and the oxygen in the air. Modern paints contain chemical additives (sometimes referred to as rust preventives) that create an invisible shield against moisture.

What year did cars stop rusting? ›

Revised cathodic automotive electrocoat primer systems were introduced in the 1970s that markedly reduced the problem of corrosion that had been experienced by a vast number of automobiles in the first seven decades of automobile manufacturing.

Does washing your car prevent rust? ›

A full service car wash can help to reduce the risk of rust on exterior surfaces as it can properly remove key elements that lead to rust. The car wash can also help renew the protective coating on the paint. As previously noted, the underbody of your car is not exempt of the threat of rust.

What is better ziebart vs Krown? ›

Over the course of a decade a Ziebart application may save you some money but as the application breaks down rust and corrosion will accelerate and the protection that Krown offers will become superior.

How often should you oil spray your car? ›

The Canadian Automobile Association recommends the oil spray method if you want to try and keep your car in pristine shape. "We would agree that an oil based product should be applied every year for maximum protection," says CAA Technical Advisor Paul Datzkiw.

What temperature should undercoating be? ›

Undercoat Application Conditions

Use when temperature is 50-90° F (10-32°C) to ensure proper drying. Avoid spraying in windy and dusty conditions.

Is underbody coating necessary for old cars? ›

In Indian road conditions, a cars underbody is most prone to corrosion. Underbody coating provides long term protection from corrosion to car's underbody. It also protects parts like internal body panels, frame rails and other inner cavities that are not physically accessible but are prone to corrosion.

What does ziebart charge for undercoating? ›

Ziebart is one of the largest providers of this method of rust protection and charges approximately $150 per vehicle.

How long does oil undercoating last? ›

Oil Undercoating is an annual application. Bring your vehicle to Autex Mazda before the winter season, and your vehicle will be protected against corrosion for 12 months in most environments.

Does undercoating ever dry? ›

Think of under coating as a type of paint that will dry faster in warmer weather and take longer in cooler weather. Either way undercoat will not harden completely and stays soft to keep out water and salt. The longer the coat stays pliable the longer it will protect the surface and deaden sound.

Is undercoating over rust bad? ›

Owners of used trucks rejoice! Here's the even better news: An oil coating can be sprayed over existing rust. It won't kill the rust, but it will cut off the oxygen needed for rust to continue. So, this is a great option for used trucks, too.

Does undercoating make a difference? ›

Undercoating effectively seals areas from the environment, abrasion, and harsh chemicals like road salt. With specialized tools and training, our skilled technicians have the ability and knowledge to seal all of the areas of your vehicle that need it and avoid all the areas that don't.


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