What Is the Difference Between Undercoating and Rustproofing, And How Much Does A Car Undercoating Cost?

When it comes to auto detailing, many people stop with just interior and exterior detailing. But there are other services to discover and try – for example, the car undercarriage protection. There are services like the rust proofing and undercoating but what is the difference between rust proofing vs. undercoating?

Rust proofing and undercoating are excellent examples of an automotive service that’s not usually heard of but is essential for better safety and protection. Some people might say that both services are redundant and just a waste of money.

But, if you want to practice excellent car care and ensure that you can make the most out of your ride by giving it the best love possible, auto rustproofing is a procedure you would have to do.


What is the difference between undercoating and rustproofing?

The first thing you need to understand is that rust forms on your car the moment you drive it out of the dealership. You need to remember that it’s so easy to make rust! Just mix iron, oxygen, and water and voila! Rust exists. Then there’s the problem of encountering salt and corrosion, especially during winter.

Since you drive your car in an environment that’s already full of these elements, it is inevitable that your ride will accumulate rust. The only thing left to do is to provide some type of structural protection to it. Check out the video below.


The great news is that the global auto industry has already created automotive technology that can give your auto a good quality barrier through products like rust inhibitors and rust converters. Brands like Rust Check are already well-known because they use quality chemicals to give optimum performance.

But with all these, advertising for these products can still be confusing. This is made harder by the fact that not many people know the difference between rust proofing vs. undercoating.

Contrary to popular belief, they aren’t synonymous and you can save a lot of time by learning how they’re both different!

So, in the article, we’ll explore:


Rustproofing Services

spray oil under car to prevent rust

You can’t choose where rust accumulates, that’s a reality you have to face. Some parts of your autobody can easily be protected but others still are not.

What rust proofing does is it treats specific, hard to reach places all over your car that are good places for rust to form. These are done by spraying a kind of protective wax all over parts that can easily chip or where moisture can accumulate.

Simply put,  rust-proofing is the treatment of specific areas all around the vehicle where rust can claim an initial foothold.

You must practice rust proofing in the exterior of your rides like tailgates, fenders, upper body panels, and etcetera since they’re very much exposed to the elements that can produce rust.

But you must not forget the interior surfaces of your car’s hood and doors since rust can oxidize from there as well.

With modern technology, rustproofing can be rapidly carried quickly. However,  the exact time needed for the process is depending on the vehicle being treated, the condition of the corrosion, the product used and etc.


Undercoating Services

Undercoating isn’t just spraying oil under your car to prevent rust! You must know its main function to fully understand and appreciate why undercoating is still needed by your car.

Undercoating is the sprayed application of a wax or rubber-based composite onto the entire underside of the vehicle. It’s designed to create a rust-proof layer between the underside of the vehicle and the water, ice, and salt of the road.

Did you know that your vehicle is already equipped with some undercoating when you buy it from your dealer?

But it doesn’t last long. Give it a year tops and you should probably remove your old undercoating and apply a fresh new layer.

Undercoating is applying a protective layer in the undercarriage of your ride. This includes the floorboards, wheel wells, and frame. Even if your car’s underside isn’t actually visible, it’s still very susceptible to damage when you go out driving.

Applying an undercoat to a vehicle plus curing time usually only takes a single day, so long as sufficient time is given for the applied coating to fully dry and adhere to the vehicle.

Mud, dirt, debris, rainwater among many other pollutants can cause you problems in the long run. By applying undercoating, you’ll get maximum rust protection and you wouldn’t have to worry for a while.

If you want to know if your vehicle needs any of the two services, you can always ask your local mechanic.


Should You Go For Undercoating or Rust Proofing?

When it comes to comparing both methods, the needs of each customer will often determine which option is best for them.

For car owners who like to see a spotless exterior may gravitate more towards rust-proofing service instead of undercoating.

However, for owners that concerned with the long-term functionality of their vehicle may be more inclined to opt for undercoating

These two treatments are far from mutually exclusive. In fact, they are excellent at complimenting each other.

Therefore, combining the undercoating or rustproofing could provide the best of both worlds of rust protection for your vehicles.

Also, it’s highly recommended to do an undercoating if your driving commute involves a lot of distances over salt-soaked highways as salt increases the speed of corrosion.


Car Undercoating and Rust Proofing Reviews

krown rust proofing cost

Here are some of the best car undercoating and rust proofing products you can check it out:

1. Fluid Film Rust & Corrosion Protection

Fluid Film 1 Gallon Can Rust Inhibitor Rust Prevention Anti Corrosion Anti Rust Coating Undercoating...
  • Rust Preventive Lubricant
  • Solvent Free, will not dry out. Long Lasting
  • Environmentally friendly. Lanolin based....
  • Anti freezing agent. Geat for snow blower...

If you want to protect your vehicles from rust and corrosion, one brand to look into is Fluid Film. This thixotropic liquid is made from wool-wax, refined petroleum oils, and other special agents that can help control corrosion. It does this by penetrating hard to reach parts of your ride up to its metal’s base.

You are assured of maximum protection! Plus, non-toxic, solvent-free, and non-hazardous making it safe and secure to use. It can protect all types of metals and can be used not just in cars but it trucks, mowers, tractors, garden tools, power tools, and more!


2. POR-15 Rust Preventive Permanent Coating

POR-15 Rust Preventive Paint, Stop Rust and Corrosion Permanently, Anti-rust, Non-porous Protective...
9,655 Reviews
POR-15 Rust Preventive Paint, Stop Rust and Corrosion Permanently, Anti-rust, Non-porous Protective...
  • ✅ CURED BY MOISTURE – The secret strength...
  • ✅ APPLICATION - Remove grease, oil, and...
  • ✅ WHEN DO I NEED THIS – Automotive, Farm,...

There are some instances where rust has already formulate before you can do some proofing. But don’t worry, rustproofing car parts even then is now easy. You can use this POR-15 Preventive Permanent Coating even with the rust intact.

You can seal it permanently and still shield your ride from further damage. This is like rust proof paint for cars since you can have the shine and gloss you want plus the repairs and prevention you need. That’s smart automotive detailing!


3. Rust Bullet Automotive Rust Inhibitor

RUST BULLET Automotive Quart - Rust Inhibitor Paint and Rust Preventive Protective Coating - No...
  • PATENTED - Awarded two United States Patents
  • LOW PREP - Little to no prep required! One...
  • DURABLE - UV resistant - no topcoat needed -...
  • EASY APPLICATION - Apply with brush, roller,...

If you’re looking for quality rust proofing products, this one from Rust Bullet fits the bill perfectly. Its coat protects your vehicle’s paint as well as prevents rust from forming. Like the POR-15 above, you can also use this even when there’s already rust.

By permanently sealing in the existing rust, you can stop it from worsening. This heavy duty and high performing product can also be used in other equipment, be it industrial, marine, or in the home.

You can also check out other brands like Rust-Oleum and Rustfre since they make quality products as well.


Rust Proofing Spray Reviews

The spray type is convenient and provides a quick fix on the spot. Here are some of the best car rustproofing sprays you can check it out:

1. Fluid Film Spray

Fluid Film Rust & Corrosion Protection, Metal Surface Penetrant & Lubricant, Marine, Automotive,...
1,956 Reviews
Fluid Film Rust & Corrosion Protection, Metal Surface Penetrant & Lubricant, Marine, Automotive,...

If you want all the advantages of the first Fluid Film product above but are wary of how to apply it, then you might like this one better. The spray type application makes it easier to use. But don’t worry, it still protects your underbody as much as the paint type.

As far as any underbody rust protection spray goes, the advanced thixotropic formula of this brand performs amazingly. So, do try it out!


2. Permatex Rust Treatment

Permatex 81849 Rust Treatment, 10.25 oz. net Aerosol Can
  • Easily applied, just brush or spray it on
  • Destroys rust on all automotive applications
  • Within minutes, rust disappears and a durable...
  • Tough coating serves as an excellent...

Now, if you want a rust preventive primer, this one by Permatex is the one you need to get! It can destroy rust that’s already forming even in hard to reach places because of its convenient spray form.

What’s more amazing is that it creates an excellent black polymer coating that protects your undercarriage perfectly. Amazingly, this coating can also be painted over!

The advanced formula in this product is specially created for fiberglass and body fillers. You can use it in other machines like trucks, trailers, fences, decks, and etcetera.


3. 3M Undercoating

3M Auto Body Depot www TCPglobal com Non-Rubberized Undercoating Aerosol 3M 8881 , Factory, 1 Pound...
  • PROTECTS METAL: Provides a tough barrier...
  • MULTIPLE APPLICATIONS: Non-paintable aerosol...
  • HELPS PREVENT CORROSION: When properly...
  • CONCEALS: Hides welding marks and other...

A great undercoating can come in forms other than an oil undercoating spray gun. It can also come in a spray bottle. This product from a reputable brand like 3M works amazingly at preventing corrosion and abrasion from damaging your underside.

It also protects an additional barrier from road debris to lessen the damage done when driving. Plus, the matte black finish helps hide welding marks and other repairs done on your undercarriage. This product also has sound deadening properties that can help reduce road noise when driving.

If you want a rubberized and paintable version of this product, you might want to check out the 3M Professional Grade Rubberized Undercoating. You can also look at other brands like Rust-Oleum for other quality products.


Ziebart Rust Proofing Cost and Review

rustproofing products

Ziebart International Corporation is one of the very first companies to introduce rust proofing to the world. In fact, they have a very long and rich history already and can be considered pioneers and experts in rust proofing.

Ziebart products can be traced back to 1959 when Kurt Ziebart, Rudy Herman, and Joe Selagi first decided to open their rust proofing shop in Detriot.

Although many people considered their innovative product to be a hoax at first, the quality and performance were undeniable. Soon, their business would take off to become the vast, globally-acclaimed corporation it is today.

Today, there are over 950 Ziebart undercoating locations to go to in over 33 countries. With all the success they’ve garnered throughout the years, you can say that Ziebart rust protection is definitely one of the best.

The cost to do a rust proofing at Ziebart depends on a few factors like the car size and type of chemical to use but a standard service should cost $200 to $300. However, it is best to get a quotation from the company directly. Check their company website for more info.


Krown Rust Proofing

Another great company to look into when searching for excellent rust proofing and undercoating shops is Krown (see this post for a mother that talks highly about this brand).

Their amazing products are highly innovative and this company continually gives importance to research and development so you know you’re getting only the best and most recent technology there is.

Since Krown rustproofing can still cost quite a bit, you may ask: is Krown rustproofing worth it? Yes!

The people at Krown are knowledgeable in what they do and they’re always willing to answer any questions you may have. Plus, you are always assured of high-quality service when you go get your car done every year.

This company is also known for its Krown rustproofing warranty, a testimony that they also care what their customers think.


What Does Car Undercoating Cost

With all the talks of these two services, the next question to ask is: how much will it cost? Is rustproofing and car undercoating worth it?

Well, to give you a ball-park estimate, a typical rust proofing service will be available for about $125 to $200. If you want other undercoating and other add-ons, you can avail $400-$500 packages.

Yes, it is pricey and you might have to save up for it; but the advantages still outweigh the price. Getting these services are always worth it despite being expensive.


Is Rust Proofing for New Cars Necessary?

clear paint protection

Yes, it is!

Some might argue that you don’t need rustproofing for car models after 2006. The reason for this is that most parts of your undercarriage are made of galvanized steel coated with zinc. Zinc does not react to oxygen so rust formation is less likely.

But the keyword there is “less likely.” There are instances that the zinc can get chipped off and then your ride will be left unprotected. You wouldn’t want that! Therefore, while you’re still at the dealership, ask for rust proofing and undercoating services.

They might cost extra but you’ll be extra protected as well.


Different Types of Rustproofing and Undercoating

There are a few options to have your vehicle rustproofed or an undercoating applied. Here are the options:

Undercoating spray

This method involves spraying a tar-based substance on the exposed parts of a vehicle’s underbody.

This tar act as a barrier to guard against moisture, salt, and other substances that can cause rust.

Though you can purchase off the shelf undercoating and rust proofing spray and DIY but getting a professional to do is better to ensure it’s done properly.

Electronic method

Using a weak electric current, this small device can stop the corroding effects of rust. You can have this device install at the dealership or source from outside.

However, this new technology has mix review on its effectiveness. So far, the electronic method does work for water automobiles but for land vehicle, it still remains uncertain.

Drip oil spray

The drip oil spray is the most commonly recommended rust protection.

Drip oil sprays tend to continue to drip once applied until they dry. This dripping can last anywhere up to 48 hours after application.

The advantage of this type of oil is that it can get into all of the nooks and crannies of your vehicle.

Dripless oil spray

A wax-like substance applied to the entire body of the vehicle, it hardens once it has dried.

The advantage is it creates a strong layer to fan off the rust but due to the spray high viscosity, it does not always get into all of the nooks and crannies of your vehicle.


How to Apply and Remove an Undercoating

While you can avail an undercoating service but you can also save some money by DIY. Without trying to reinvent the wheel, the guys at Your Mechanic has done a good job in summarising out the steps:

  • Clean the underbody. Start by cleaning the underbody of the vehicle.
  • This requires you to put the vehicle up on a hoist.
  • Using a degreaser, clean the underside of the vehicle.
  • Next, remove all rust from the undercarriage using a grinder. Make sure to wear eye protection when doing so.
  • Sand any remaining rust using sandpaper designed for metal. You need a sandpaper with a grit of at least 220 or larger.
  • Wipe away all of the dust created from grinding and sanding.
  • Paint and prime the underbody. After removing any rust, it is time to prime and paint the underside of the vehicle.
  • Start by priming all of the areas you cleaned of rust. One of the best primer types to use is a high zinc primer. Allow the primer to dry.
  • Your next step is to paint over the primer with black automotive paint. Allow the paint to dry.
  • Undercoat the underbody. The last step in the process requires you to apply an undercoating to the underbody of your vehicle.
  • Apply the undercoating liberally to the underbody of your vehicle. Make sure to apply it to every part that you expect to be exposed to the road. Allow this coat to dry for at least an hour, or longer if the instructions call for it.

Read the full process at Your Mechanic.

  • Updated May 10, 2019
James Evans

As a passionate outdoorsman and an automobile enthusiast, James spent most of his time in his garage tinkering with cars and bikes. During his free time, he loves to hike and blog about the things that he has done to keep his ride in tip-top condition.

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