How To Prevent Vehicle Rust From Getting Worse

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Close up of the rust forming on the rocker panel of the vehicle

A rusting car is a scary thing. Once you see the first signs of rust, it might be too late. When rust goes too far, you have no choice but to scrap your car since it will be unsafe (and illegal) to keep driving it. For that reason, you want to prevent vehicle rust from getting worse.

The best way to prevent rust from getting worse is to tackle the rust currently on your car. You should use an assortment of rust removers, sanders, fillers, primers, and colored paints to fix the area. Once the rust is removed and masked, it’s much less likely that the rust will spread to the rest of your car.

In this guide, I’ll show you how to do that. Professional detailers have a few techniques that they use to eliminate and minimize the impact of rust on a car. Keep reading and I’ll show you these techniques.

How Does Rust Start?

Rust is actually a chemical process. It’s also called oxidation because it’s the result of oxygen interacting with metal when water is present. The combination of these three things results in iron oxide.

If you’ve been to an old playground, you’re very familiar with rust. It’s a little misleading, though. Even though rust shows up in a lot of places, it’s a dangerous product.

Rust isn’t just a sleeve that forms on top of a metal, it’s a chemical reaction that eats away at the metal. Iron oxide can only form when metal is sacrificed.

Close up of surface rust bubbling on the outer skin of the car door
Surface rust bubbling on the outer skin of the car door

Keep in mind if there is visible surface rust, there can be much more rust hiding on the other side of that metal panel. It’s best to take off interior panels if needed to see the extent of how much rust there is.

My friend had a trampoline growing up that was never covered. One day, we noticed all the springs were rusted over. He grabbed one of the springs and squeezed, and the spring snapped in half. That’s because rust had eaten away the original metal and hollowed it out.

Rust starts any time metal is exposed to water and oxygen. Basically, any metal outside that isn’t covered is susceptible to rust.

What’s So Bad About Rust?

Rust is a silent killer of vehicles. A lot of old farm trucks wind up getting rusty, and the rust will eat away at the framework. Car inspectors are taught to look for rust and see if it is doing structural damage. If enough rust is present, the inspector will fail your car and it will no longer be a street-legal vehicle.

Excessive fender arch rust with metal already compromised on close up on a blue car
Compromised fender needing to be replaced due to excessive rust

The science behind rust is scary. While it might look like a collection of new material on top of your car, it’s actually the result of your metal eroding away. The rust literally eats away at your car’s metal and leaves holes.

It Unsafely Affects Your Framework

If one of these holes gets to your car’s frame, then your vehicle could be compromised. A hole is a big no-no when it comes to engineered structures, and cars are no exception.

Another bad thing about rust is that it’s hard to stop it once it starts. If you just brush away the rust with your hand, you’re not slowing anything down. The rust will continue to spread and eat away at the metal.

In the right (or wrong) environments, rust will entirely destroy metal until there’s nothing left. Your car’s frame is the only thing keeping it together and keeping you alive during an accident.

Rust Can Ruin Your Engine Bay

If rust appears on your car’s hood, you’re in trouble. Your engine bay isn’t waterproof, and a lot of the components are susceptible to water (like your battery, pumps, and wiring).

PB Blaster 16-PB Penetrating Catalyst 11 oz. – 2 Cans

PB Blaster 16-PB Penetrating Catalyst 11 oz. - 2 Cans
PB Blaster Rust Penetrant – great for seized bolts and any metal components

Parts will be much harder to fix and ultimately replace. Brake lines will seize up, bolts will refuse to come out unless you use something like PB Blaster, basically metal parts will begin to fuse to each making it much harder overall to surface anything mechanically.

Rust Destroys Your Undercarriage

Under your car, most of the parts are made of untreated metal. They aren’t built to be corrosion-proof because it doesn’t really rain on these areas. The worst thing that happens is you drive over a puddle, but that water is quickly wicked away by the wind.

When moisture finally gets to your car’s undercarriage, rust can start forming quickly.

It can sometimes be tricky to find this rust unless you put your car on a jack and actively look for it. If your oil pan gets rusted, then you’ll lose oil, and your engine will seize. That’s a big problem.

Coatings On Your Car Prevent Rust

I mentioned that rust happens whenever metal is stored outside. Well, cars are made of metal but not every car is covered in rust.

That’s because of your car’s topcoat. Auto manufacturers realized pretty early on that exposed metal is a terrible idea when it comes to making cars.

Instead, every car has a composite of a few different materials on top of the metal. Throughout the 20th century, especially in the ’70s & ’80s, car manufacturers began implementing and improving galvanized steel to prevent rust.

The base layer is the raw metal used to make cars. The metal is covered with an e-coat and pretreatment. Both of these layers prevent corrosion and keep other layers stuck to one another.

Car being painted in the assembly production line at an assembly plant

Next, you’ll find a layer of primer. This adds some durability to the car, prevents UV radiation, and smooths everything out.

On top of that is a layer of colored paint. That’s why your red Ferrari looks red in the first place.

After the colored paint, there’s a thick layer of topcoat or clearcoat. It’s about 2-5 times thicker than the layer of colored paint, and it serves a single purpose, to keep your car safe from environmental damage.

However, all of these layers together only equate to about 1/250 of an inch. That’s microscopic.

If any amount of damage goes deeper than this, your car is susceptible to rust. After all, these surfaces are the only thing preventing it in the first place.

Ways to Prevent Vehicle Rust from Getting Worse

Now, let me dive into some of the best ways to prevent vehicle rust from getting worse. It’s important to try out these tips so that the rust doesn’t take over your car and ruin it.

Use a Rust Remover

You’ll find a lot of rust removers on the market. Their sole purpose is to get rid of rust from metallic surfaces.

I’ve used these on my vehicles in the past, and they actually work. Each product is a little different and has different requirements before you use them.

Rust Converter and Primer – Quart (32 Ounce) – One-Step to Remove Rust and Prime Surface

Rust Converter and Primer - Quart (32 Ounce) - One-Step to Remove Rust and Prime Surface
Rust Converter and Primer – 32 oz.

Some products you can just spray right on the rust and rub it away, but others need you to sand and prep the area before anything else.

Once rust is present, it’s going to get worse until it eats through your car’s body. By removing the rust, you stop this vicious process.

Park in a Garage

One of the best ways to avoid rust is to keep the car away from moisture. How can you do that? By parking in a garage overnight.

If your car is left outside overnight and it rains, that moisture will just stick around your vehicle. From there, your vehicle soaks overnight, and any rust that you currently have will get worse.

In fact, that might have been how your car started rusting in the first place.

In a garage, the temperature and humidity are much more favorable. You should use a garage or covered parking whenever possible.

Avoid parking on grass for prolonged periods

Early in life, I learned that parking on grass is a bad idea. For one, you could wind up getting stuck (follow my guide for getting un-stuck, if you are), but you’ll also be more susceptible to rusting.

Grass does a great job of hanging on to moisture in order to keep the blades healthy. The negative side effect of that is that you’re parking in a field of moisture.

VW Volkswagen Golf parked on the grass near the water red color

Most of your car’s undercarriage is made of unprotected metal. As your car stews in the wet grass overnight, droplets will evaporate and condense on your car. In other words, any rust that’s near the bottom of your car will just get worse.

This is more obvious if you wake up and notice dew on the grass. That same moisture is attacking your car whenever you’re parked in a grassy lot. It’s best to park on asphalt or concrete.

Use a Car Cover (Properly)

If you don’t have access to a garage or covered spot, the next best thing is to use a car cover. When you use one correctly, it will prevent rust.

In fact, there are a lot of other benefits of using a car cover. It’s an expensive and portable way to keep Mother Nature away from your car. Pollen, moisture, and bird droppings can make rust much worse.

Before buying one, make sure it has the appropriate dimensions to fit your car. If it’s too loose or tight, you could cause rust by allowing moisture to get trapped or settle on exposed parts of your car.

Also, it’s worth splurging for a more expensive car cover that uses more desirable materials. This will keep your car scratch-free and protected from UV rays.

Routinely Wash Your Car

If something acidic sits on top of your car for too long, rust will form. One way to keep harmful materials away is to routinely wash your car.

Experts suggest that you should wash your car every two weeks or so. It should be done more often for cars that have to park outside, especially in high-humidity areas like Florida.

Car being washed outdoors in the winter time

Remember to completely dry your car after washing it by using a series of microfiber towels. Leaving water around to airdry certainly won’t help when you’re looking to prevent rust from spreading.

To wash your car, just use a bucket of water with automotive shampoo in it. Use microfiber towels or mitts to wipe down your car and rinse it clean afterward.

Sand and Paint the Rust

One of the easier and more efficient ways to prevent the spread of rust is by sanding and painting the area.

Sanding is used to remove all the oxide that’s built up on your car. Be careful that you don’t start removing the metal from your vehicle.

After that, you’ll want to protect, seal, and colorize the now-exposed metal. Start with a little filler in any holes that are going through the car. This will fill the gaps. Using glass fiber repair paste is a quick way to fill it.

From there, add a paint primer. This keeps the metal corrosion-resistant. Once dried, cover the primed area with paint that matches the rest of your vehicle. 

Repair Your Topcoat

If your vehicle gets a scratch that goes through the topcoat, you’ll want to fix that. Deep enough scratches will break through the corrosion-resistant layers on top of your car’s base metal. Without this protection, there’s nothing stopping your car from rusting.

A professional detailer polishing the car with an orbital polisher with red LED lights in the background

These repairs can get pricy if you go to a professional. However, it’s often the best way to fix the issue.

For simple repairs, a professional might charge around $500. For extreme cases, the price can go up to $10,000 and beyond. In that case, you’ll need to ask yourself if your car is worth fixing.

Try Some Bondo

Bondo is an old-school filler that’s made out of polyester putty. Growing up, it was my buddy’s best friend on his rusted-out Camry.

The idea is that you can remove the rust and put Bondo over the rust. It will prevent rust from getting worse and can be smoothed out and painted.

If you do the job right, the once-rusted area will be indistinguishable from the rest of your car. All you need is a nice sander, primer, and paint that matches the rest of your car.

Keep Road-Salt Away

During the winter months, you need to be extra vigilant when it comes to washing your car. Road salt and brine are highly acidic and will eat away at your car.

A man washing his car with a pressure jet washer in the winter

On an almost-weekly basis, you should be washing your car and removing these products from your vehicle. This is even more important if you already have rust on your car. If the salt goes into these rusted areas, it will speed up the corrosion process.

At the very least, you should wipe away the salt from your car with a microfiber towel after driving on salted roads.

Wax Your Car Twice a Year

Wax adds another layer of protection on top of everything else. Once applied, it will sit around for a few months and keep your car protected and shiny.

After using a rust remover and cleaning your car, you can wax over the rusted area, and it will stop spreading.

Fix Scratches Before They Get Worse

A lot of times, rust starts with a scratch on your car. If you look at a timelapse of rust forming on a car, it starts with a scratch or hole and just grows from there.

Before and after image showing how car polishing removes the swirl marks and scratches on the surface of the paint

That means that you want to fix scratches before they get worse, and rust starts. You can do that with a number of scratch repair products. I have an in-depth guide that covers how to remove scratches, so I suggest starting there.

Once the scratch goes away, your car is more likely to avoid rust.

Look for Bubbling Paint

Bubbling paint is actually the first sign of rust. When you see bubbling, chipping or pitted paint on your car, alarm bells should ring in your head.

Of course, it’s always best to catch rust early. If you jump on it before rust is visible, then you’ll be able to prevent it from getting worse.

If you see bubbling paint, you’ll need to remove the paint and apply a rust remover as soon as possible. Sand the area, then go over the area with a primer and colored paint that matches the rest of your car.

Routinely Check for Rust

You should check for rust every time you wash your car. Some of the high-traffic areas for rust are alongside the skirts of your car, the hood, and around door panels.

Mechanic closely examining the vehicle from underneath the car on a hydraulic lift inspecting for any rust or damage

As you wash your car, you have an opportunity to get up close and personal with your vehicle’s bodywork. Check for bubbling, cracking, or pitting paint. In addition, check for more obvious signs, like reddish-brown rust or holes.

Take it to a Pro

If rust is getting serious on your car, you’ll need help from a professional. I’d suggest going to a body shop instead of a mechanic in this case.

The body shop has experience working on the body of a car, so they’ll have the right tools and expertise to help you out.

Professional auto shop repair sanding down and getting the rear quarter panel of the car ready for paint after doing rust repair

Start off by getting a quote. There’s no way to estimate how much it will cost you without seeing how bad your car is, first. It could be a few hundred bucks or a few thousand dollars. It really depends.

If you want my advice, I suggest getting at least three quotes from three different body shops. This will help you understand which shop is trying to scam you, and which ones want to help you. If all three quotes are about the same, then pick whichever option you want.

Most of the time, I would pick whichever quote is in the middle.

Conclusion

As you can see, it’s not a difficult process to prevent vehicle rust from getting worse. It’s definitely tedious, but not hard. Try out some of the tips that I listed in this guide, and let me know how they worked for you.

If you want to learn more about DIY car repairs, explore my site. Be sure to check out my list of recommended car products.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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