Is undercoating a used car worth it?

Undercoating any car will ensure that the car is protected from rust. A newer car is sometimes covered by specific warranties straight from the factory which means that there is no need for any additional rustproofing while the warranty is still intact.

Undercoating a used car on the other hand seems like a more logical idea. Especially so if you plan on keeping the car for a while. If you live in a climate that experiences lots of adverse weather conditions, or there is lots of salt on the road, rust-proofing is highly recommended.

But many people believe that undercoating should be a proactive measure, not an active one. This means that you should coat your car before it even leaves the dealer’s lot, and used car undercoating makes less sense because a used car has already been affected by rust to a certain degree.

No matter if you own a brand new car, or a used one, undercoating it offers an additional layer of very welcomed protection. You can successfully coat a used car if you grind and sand out all the rust spots before applying the undercoat. If done right, there is no difference between coating a new or a used car.

What is undercoating?

Undercoating essentially blocks oxygen and moisture from reacting with bare metal not to cause any corrosion or rust spots. It is an evenly and thoroughly applied protective film placed onto the car’s undercarriage that protects the undercarriage for a long time.

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An underside of a car is a fairly vulnerable part of a car because of the constant moisture exposure. If you pair that with constant stone chipping and substandard road surface quality, the undercarriage of a car can get severely beaten up after a few years, which results in rust and corrosion.

There are a few different methods of rust protection, and undercoating is one of the most common ones. Undercoating consists out of applying a tar-based substance onto the vulnerable areas. Drip/Dripless Oil sprays are also a fairly common way of rust-proofing a car.

All three of these cost from $100-200, and they should be repeated every year. All three of these use substances that harden after they have been applied in an effort of sealing all the vulnerable areas. It is paramount that these are applied onto a clear surface, otherwise, they might even worsen the problem.

Undercoating a used car

It’s not true that all used cars have already been severely affected by rust beyond repair. Such areas have to be grinded out, sanded by a fine grade of sandpaper, degreased, primed in, and painted before applying the undercoating solution.

Undercoating does not only protect your car from rust and corrosion, but it also protects the already damaged areas. And the extra layer of protection for a used-car makes more sense compared to a newer car, especially so if you consider that most newer cars are indeed covered by some kind of a warranty.

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Some parts of the world are affected by corrosion more than others, and if you apply the coat as recommended, you may even lower your insurance premiums. Furthermore, if your car is protected, it might also retain more value, which is extremely beneficial when it comes time to sell it.

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Differences between rust proofing and rust protection

Not many people know that these two terms are not the same. Rust-proofing consists out of applying a layer of mostly rubberized sealant products or any other rust repelling coating on specific surfaces that are considered vulnerable.

Rust protection on the other hand is a process in which a manufacturer infuses specific rust inhibiting properties into the panel itself. And that’s the difference between modern cars and older ones. Newer cars use more aluminum and galvanized steel, both of which are known for rust-repelling properties.

These materials are inherently less prone to rusting, especially so if they are coated with a sophisticated e-coat that consists out of electrically charging the car’s body panels in an effort of making the panel less likely to react with moisture and oxygen.

Some forms of rust-proofing like a strategically placed electronic module that sends out a constant electronic current are made to offer the same results as a factory e-coat. All of these rust protection measures are fairly new, which means that lots of used cars don’t offer such properties.

FAQ Section

Are undercoating solutions toxic?

Like many other chemical-rich products, undercoating solutions are indeed toxic, especially so while in a non-hardened state. This means that you should always use protective equipment such as eyewear protection and gloves at the very least.

Some studies have shown that the levels of toxicity are incredibly high, which means that you should always take great care when handling these products. This is also a reason why you should leave such things to an experienced professional.

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How well do the electronic rust-proofing modules do?

Strategically placed electronic modules that sent out a constant electrical current throughout the car’s panels seem space-age, but this technology has been around for quite a while now. Metal surfaces found on underground tanks and boats are protected by these modules for decades.

But the difference is that these surfaces are almost always wet. This means that the signal conduction is always powerful, but the car’s body panels are not always wet, which means that this method of protection is not necessarily the best choice when it comes to cars.

How long does an undercoat last?

Most undercoating solutions last a year or two. Some of them can last even longer, but in general, you should inspect these out after a few months or so. If you pay more beforehand, and you’ve done all the things necessary before applying it, it might even last you for a few years.

It all depends on how often the car is driven, the weather conditions, salt accumulation, quality of the undercoating, and coating application. Just make sure you inspect the application every few months or so, and if you encounter any cracking, be sure to remove the coating, and apply a new one.

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    Marko Mikulic

    Why do you love writing about cars? I love writing about cars as cars are a huge personal interest of mine. I was raised in a car enthusiast community and ever since I was young, I always wanted to do car-related work.

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