You can buy the most expensive car. You can stick religiously to the maintenance schedule and take best possible care of it. If you feel strongly about it, you can even pay for expensive protection measures. And yet, one simple truth remains:
All cars rust eventually. And there’s nothing you can do about it.
That may come as a surprise. After all, we often associate corroded metal with a distant past when rust would eat away huge chunks of steel and it wasn’t uncommon for a brownish hue to infect vehicles after only a few years.
And yet, rust never went away.
It may arrive later in the lifecycle and it may no longer be as aggressive as it used to be. But if you’re under the impression that you can just lean back, you’re mistaken.
In this special, we’ll go into depths about what to look out for when it comes to rust. We’ll explain why modern materials are better at fending it off, what kinds of rust there are and what causes them. And finally, we have some suggestions for you on how to spot and fight rust.
Table of Contents
- Aesthetics are not the only problem
- Rust problems hit rock bottom in the 70s
- One of the earliest methods to protect cars consisted in ‘undersealing’ them
- The magic word: Galvanisation
- Improvements in design
- Three kinds of rust
- What will cause rust?
- How to check for rust
- How to protect your car from rust
- Wash your car regularly
- Wax your car regularly
- What is professional rustproofing?
- Take action to prevent rust from spreading
- Reliability vs rust-free-design?
- Rustbuckets: Avoid these models!
- Cars that never rust
Rust isn’t just ugly …
Rust isn’t a pretty sight. Having to watch it eat through the beautiful paint layer of your cherished car is painful. What starts out as small reddish spots can quickly affect larger areas. It’s almost as though your car is suffering from a skin disease.
Aesthetics are not the only problem, though.
Far more importantly, rust is actually dangerous. Just think about it: Corroded metal can become porous, soft and weak. As a result, the structural integrity of your vehicle can suffer. Parts can break off. If those parts happen to be important, you’ve got a serious problem.
Safety is one aspect of it. You don’t want to be driving around with a car that’s about to fall apart, after all. Finances are another issue. Rust won’t stop and will actually spread. So you will often need to replace affected parts completely. That, it goes without saying, can be quite expensive.
A rusty past
If you’ve ever driven or seen a car from the 60s or 70s, you’ll know how much progress has been made in terms of rust protection. Back in those days, cars would rust a whole lot sooner. And there was a lot less you could do about it.
Once the rot had set in, the fate of your car seemed determined. In fact, ensuring adequate rust-protection was one of the most important points for a manufacturer to differentiate herself from competitors.
In some respects, rust problems hit rock bottom in the 70s.
During that decade, manufacturers began speeding up their launch cycles. They no longer produced cars that would last a lifetime, but merely until the next generation arrived at dealerships. One of the changes: They used thinner body steel. As a result, the effects of rust were far more visible.
The 80s saw mild improvements. But it wasn’t until the 90s brought advances in production technologies that rust became a far less dramatic issue.
That said, in China and India, many of these advances are still not applied today. Cars still rust pretty heavily there accordingly.
A thin border
To understand how contemporary rust protection works, it is vital to understand what rust actually is.
If a car rusts, its steel is reacting with the oxygen of the air in the presence of moisture. Without water, there can be no rust, As a science website explains:
“Rusting cannot occur without both water and oxygen. Water helps iron react with oxygen by breaking up the oxygen molecule.”
The more exposed the naked steel is to the air, therefore, the higher the chances that corrosion will occur. Before the arrival of modern rustproofing, the only thing that stood between a car’s body and the elements was the paint.
Once that layer had been damaged or worn down, it was often already too late.
One of the earliest methods to protect cars consisted in ‘undersealing’ them.
This means applying a thick layer of ugly, but tough and protective paint to some of the hidden areas of a vehicle. It includes, for example, the entire underside of the body, where it doesn’t really matter if things don’t look pretty.
Of course, eventually that additional layer would also get damaged. So even undersealing could not stop rust from forming. And form it did – and usually quite quickly. Things looked pretty dire for a long time. Until someone came up with a smart idea.
The magic word: Galvanisation
The basic idea behind galvanisation goes something like this: Rust is oxidised steel. Paint can protect the steel, but only for as long as it’s perfectly intact. Other than that, though, steel is still a great material for a wide variety of reasons. So wouldn’t it be a much better approach to simply improve it so it oxidises less quickly?
Essentially, that’s precisely what galvanisation does: It treats the steel so it becomes less reactive when exposed to the air.
There is a magic ingredient to galvanisation: Zinc.
During the production process, every car body is dipped into a pool of hot zinc before it gets painted. The zinc is so hot that it is molten and will accordingly stick to the body like a second skin.
At first, this merely seems like a more elegant version of undersealing.
But there are a few reasons why galvanisation offers a far better protection than paint ever could:
- For one, it adds yet another barrier which the oxygen would have to cross.
- Zinc reacts with the air faster than steel. As Autoexpert explain: “Because zinc is more active than the underlying steel, the zinc sacrifices itself so that the steel will live longer. That doesn’t mean that the steel won’t corrode. It really does depend on the operational environment of the steel. The zinc will protect the steel for as long as the zinc is available.”
- Amazingly, this protection even works if there is a small hole in the protective coating. If there is enough zinc close by, it will still react with the oxygen and thereby keep the steel from rusting.
Galvanisation is no miracle cure. But it has had a powerful effect on the longevity of cars. According to Jay Samuel, a senior lecturer in the UW–Madison department of mechanical engineering, “a lot of industries have improved, but the auto industry has done the best” in fighting corrosion.
Improvements in design
Galvanisation has clearly been very effective. And yet, over the years, manufacturers came up with quite a few more ideas on how to make it even better. Some of these related to how rust forms in the first place. We’ll get into this a little deeper in a bit.
Essentially, the likelihood for rust increases wherever there is friction: Friction between moving parts, friction between aggressive substances and the car body. This is why rust preferably occurs at parts with hinges or in pockets where those aggressive substances can freely accumulate, such as in the pockets of wheels. Also, as the University of Winsconsin notes:
“Metal has been replaced with rustproof plastic, especially at the rust-prone rocker panels below the doors. The removal of stainless steel and chrome-plated trim has cut galvanic corrosion, which occurs when different metals that touch each other generate a small electric current.”
Thanks to the combination of galvanisation, the use of alternative materials wherever feasible and smart design improvements, rust has been on the retreat for a while.
Three kinds of rust
For practical intents and purposes, however, it makes sense to make a few distinctions.
If you think about it a little deeper, there are actually three kinds of rust, each with their characteristic profiles and problems.
Firstly, there is cosmetic rust. It manifests mainly as tiny bubbles on the paint surface. Although very unappealing to look at, cosmetic rust is usually not a major issue. Affected spots frequently remain localised and will only spread if you allow them to. As an expert states: “This type of corrosion does not usually cause concern as it can be easily repaired with proper body preparation and re-painting.”
Then, there’s rust which spreads beyond local spots. There is no clever technical terms for this. But regardless, it’s a far more serious issue. You can still turn the tide. But you will need to act fast.
Finally, there’s frame rust. This is the worst kind by far. Frame rust threatens the integrity of the car. It can cause parts to snap or break. It goes without saying that if it occurs at vital places like breaks or gas lines, the consequences can be life-threatening.
If you spot frame rust while looking for a used car, you should head for the door straight away. Although frame rust can be repaired, it requires expensive repairs. And even then, there are no guarantees it won’t return.
What will cause rust?
We already touched on this question a bit earlier on. But since rust will always remain an issue in some form, it makes sense to dedicate a little more space to this question. If you know what causes rust, after all, you will be able to take counter-measures early on and ideally prevent cosmetic rust from turning into frame rust.
There are a handful of reasons for rust. Some of them will surprise you. So will the absence of others.
Rust is caused by the direct exposure of the car’s steel to the oxygen of the air. So everything that increases that exposure is bound to have a negative effect.
Accidents are quite probably the most serious cause for rust to form. If something as inconspicuous as a small stone can chip away part of the protective paint layer, you can imagine what a far bigger impact, such as a collision with another car, will do.
Of course, the most important thing about accidents is that you are not physically hurt. But once you’re okay again, make sure to restore the “health” of your car as well. Make sure that no open surfaces remain and check if rustproofing is in order.
Wherever parts are rubbing together or where they are connected by hinges, rust can form a lot easier. The rubbing has an abrasive effect, which causes paint to flake and thus exposes it to the air. Wikihow identifies typical areas where components meet as “the door frame, where the hood meets the fenders, and around the trunk.”
Canadian website Ridetime adds to these the following:
- Engine enclosure
- Doors and around windows
- Lower body panels
- Underneath the trunk carpet
These areas are indicative of the overall rust state of the car. So much so, in fact, that Ridetime claims:
“If these areas are clear of rust, chances are that the rest of the car is also rust-free.”
Dirt in general and bird droppings in particular were the most common source of rust in the past. Bird droppings are highly acidic, which means they can burn through the paint over time, if left unremoved. Ultimately, they’ll reach the steel underneath this way.
Today, the threat from dirt is a lot smaller than it used to be. The double protection from significantly improved paint layers and the zinc added during galvanisation means that even without a weekly cleaning, the danger of rust formation should be fairly limited.
That said, it would be careless to simply trust things will be okay. Every car deserves a regular visit to the car wash. We’ll talk about that in the final section of this article, when we discuss ways to protect your vehicle against rust.
Climate / Weather conditions
Climate remains one of the most important and underestimated factors for rust until the present day.
The weather plays a role in causing rust in three distinct cases:
- Heat exposure can speed up oxidative processes. So if the Summer is very hot and your car is exposed to a lot of other risk factors, rust has a higher chance of taking hold. On the other hand, heat in itself will not cause rust.
- In very cold Winters with plenty of snow, there will be more salt (or, alternatively, potentially harmful chemicals) on the roads to prevent wheels from slipping. Salt, like heat, facilitates the corrosion process. Add to this the increased danger of stone-chipping on snowy roads and you’ve got a recipe for potential disaster.
- In some areas, the soil is considerably more acidic than in others. Russia is a case in point. Here, a higher level of rust protection would be in order.
There is little you can do about climatic influences. What you can do, however, is to deal with rust issues quickly if they do occur.
How to check for rust
If you’re intending to purchase a used car and splurge on a vehicle inspection, a rust check will usually be included. In fact, it is one of the main reasons why such tests can make sense: Because you can trust in the experienced eye of an expert.
On the other hand, even if you don’t have the cash to pay a mechanic, there is no reason to despair.
To help you along the way, here’s an overview of the most important steps. By following these, you should be able to detect rust early on and take the appropriate measures.
Check the bottom of the car first
If you think about it, it’s perfectly clear why the bottom of a car should start to rust first. The components you’ll find here are all moving. Many of them feature steel rubbing against steel. They’re exposed to dirt, salt and acidity far more directly than most other areas of a vehicle. And most of them do not have an additional layer of paint to protect them against corrosion.
So how do you check for rust underneath a car in practise?
“If you have concerns about rust, allow the seller to let you take the car to a mechanic, who can put it up on a lift. Once the car is on a lift, you can poke around underneath it to see if you can find any rust. Common rust spots include the frame rails, which run underneath a car’s doors on each side, the wheel wells, the exhaust, the suspension and virtually any other underside components made of steel or metal.”
Use a flashlight to inspect wheel wells
Wheel wells, as we indicated above, are a natural breeding ground for rust. Just like the bottom of the car, they are exposed to the various rust-causing elements. They also create pockets where these can accumulate and create even more damage. Finally, they are hard to inspect, which means that you may not spot the rust issues in time.
A very easy solution is to inspect wheel wells each time you take your car to the car wash. Using a flashlight, you should be able to detect early signs of rust and to make sure it doesn’t spread.
Look for signs of repainting & repair
Accidents can wreak havoc on a paintjob. Mechanics can improve this by repairing the car and making sure it is properly protected against rust again.
In some cases, however, repairs are not performed properly. Using body filler can save many Pounds worth in repairs. But it will also offer a lot less protection. And a botched paint job can cause serious damage.
Even bad repair jobs can be hard to spot sometimes. Make sure to take a close look at the car. Especially, if the MOT history or the car history check suggest that the vehicle has been involved in an accident. You can check for body filler by holding a magnet against spots where you’re in doubt. If the magnet won’t attach to the steel, you know something’s wrong.
(The exception are obviously car bodies made from a different material. In the USA, for example, companies like RAM have started building their SUVs from aluminium, which has its very own advantages and problems.)
How to protect your car from rust
Clear enough, rust can have a destructive effect on your car. It can reduce its longevity and seriously impact its resale value. Dealing with it efficiently is therefore not just about preserving the beauty of your vehicle. It is also a sensible financial decision.
When it comes to rust protection, there are a few questions that we need to address first:
- How often do you need to rust proof you car?
- Can you deal with rust yourself or should you leave things up to an expert?
- How much will rust protection cost me?
First of all, there is a common misunderstanding that you need to rustproof your car every year. Writes hotcars:
“The important thing is to get a company and qualified personnel to perform this type of procedure on your vehicle. If the person does it correctly, the result can last a couple years, (or even a few). A high-quality rust-proofing job should last up to ten years.”
Other jobs, such as giving your car a regular wash-down, can and should, on the other hand, be performed more regularly. While rustproofing should ideally be done by an experienced mechanic, you can deal with the latter yourself.
Will it be expensive? Not necessarily. Of course, some care products will set you back a few Pounds. But costs should not be excessive. And in the long run, the money spent on rust protection is sure to be less than the costs caused by rust and its effects.
Let’s now turn towards the steps you can take to protect yourself against rust.
Wash your car regularly
Surprised? You’re not alone. A lot of drivers are under the assumption that water is a catalyst for rust. And, as we established at the outset, it is.
And yet, it is also an ally in your fight against rust.
Think about it: Rust forms more easily if the paint layer of your car is damaged or brittle. Dirt damages the paint layer. So by washing it off before it starts reacting with the paint, you are actively protecting your car.
The one thing you obviously need to do is wipe off excess water and moisture after you’re done.
For more information, see our expansive article on car wash recommendations.
Wax your car regularly
Undersealing has a few downsides, unfortunately, one of them being that it makes your car look bad. Fortunately, there’s a way of reaping the benefits of undersealing while making your car look even better.
Waxing your car is, in a way, over-sealing: You apply a layer of wax on top of the paint. For as long as it stays intact, this will ward off dirt and debris and thus prevent the steel from reacting with air and water.
How often should you wax? If you like the look of wax on your car, you can easily do this 4-5 times a year. If you mainly care for the rust protection it provides or if you simply feel it’s too much work, twice is enough.
What is professional rustproofing?
Professional rustproofing is similar to waxing in that it also applies a protective layer on top of the paint. Only, it uses a different product, which will keep its protective effect for longer.
The trick with the product is that it needs to get to the places where moisture gets as well. But it should not seal these spots off entirely. By sealing an area, after all, you’re not just preventing moisture to come in, but also preventing it from coming out. So if condensation occurs, you’ve got a major problem with trapped water. This is why garages use specialised products which will offer as much protection as possible without entirely closing off the surface.
There are different levels or protection. With a softer product, you may need to drop by your garage every 1-2 years. With a tougher, rubberised layer, you can extend that cycle to once a decade.
Take action to prevent rust from spreading
First of all, don’t panic. There really is no reason to. If you discover rust in time, there are many things you can do. And if your vehicle has been galvanised, this will prevent the rust from spreading very quickly.
Wikihow has a few suggestions on how to keep the rust in check:
- Scrape rust off with a razor blade or fine grit sandpaper.
Rust is infectious, so you need to get it off your car. Use soft sandpaper and make sure to only cover the rusted areas without touching the paint. Sometimes, it can’t be helped, but if a little paint comes off, that means it has probably already been affected as well. You may need to repaint the rusted posts either way.
- Apply rust arrestor to prevent the further spread of rust.
A simple over the counter product will do. Rust arrestor stops rust dead in its tracks and prevents it from spreading even further. Carefully apply a thin layer to the affected area and then allow it to dry completely.
- Use automotive primer
The primer will cover up the area and prepare for it to get repainted. It’s a bit like applying make-up to your car!
- Apply touch-up paint to the primer
Make sure you find a tone that pretty exactly matches your car’s current colour. Even small deviations can look unprofessional.
Reliability vs rust-free-design?
This question is not quite as naive as you might think. Even today, in an age where rustproofing has become the norm for pretty much every car in Europe and Northern America, there are still notable quality differences between different brands.
So your choice of make and model definitely play a big role in trying to keep rust to a minimum.
When it comes to rust, you will need to unlearn everything you learned about reliability. Reliability and rust-free-design are two entirely different things. As Afrinik.com comment, “German car manufacturers such as Audi, VW, Mercedes and BMW have proven to protect their products against rust. As well as the French manufacturer Renault. However, the Japanese, widely acclaimed because of their high reliability, have considerable rust problems.”
Let’s take a closer look as we dive into the most notorious rust buckets and the leading rust fighters available right now.
- Toyota Rav4: An exception in Toyota’s catalogue, but unfortunately the Rav4 does seem to experience rust issues.
- Range Rover Sport: Its rust issues may not matter to most of us, since this otherwise amazing car is simply far to expensive to even consider.
- Ford Ka: It might seem like an interesting choice, since used Kas are pretty cheap. Unfortunately, the same applies to their rustproofing.
- Ford Focus: One of the UK’s most popular cars suffers from rust problems.
- Mazda 3: Mazda has considerably improved its rustproofing, but the 3 still suffered from some serious issues.
If you want to avoid a rusty lemon, you will need to do some research. Typically, rust does affect all model generations equally.
This is very apparent with a brand like Mercedes. For years, the German premium car maker’s products were indestructible and class leaders when it came to rust. Then, management decided to cut costs and quality dropped accordingly. This is why you will find rusty spots on quite a few 90s Benz’. Things improved and today, Mercedes is back in top shape again.
Cars that never rust
This is a list of the cars with best rust protection:
- Kia Forte: Great to hear excellent rustproofing doesn’t need to cost the world!
- Volvo S60: For once, reliability and rust protection do go hand in hand.
- Volkswagen Golf: Not just one of the greatest cars ever built – also one of the most rust-free ever.
- Audi A3: Audi will also lie outside the reach of most readers. Still, it is nice to see premium prices actually delivering premium rust protection for once.
- Honda Civic: Surprising? Not really. Honda has improved its image over the last years and the Civic proves this with excellent anti-rust properties.
Of course, even these rustbusters will eventually rust. As we said at the beginning: On a long enough timeline, we’re all due.