5 Tips to Prevent Your Car from Rusting in Winter

Rust is your car's enemy, and road salt is its sidekick, but you can keep both at bay.

Ronan Glon | 

Feb 22, 2023 | 6 min read

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Once rust starts, it doesn't stop. Over time the corrosion process can wreak havoc on your vehicle. It's ugly, it weakens your car's structural integrity—and it can do just as much damage to your resale value.

But there's good news: Rust isn't inevitable, and there's a lot you can do to prevent it.

"While most modern consumer passenger vehicles offer far superior rust resistance from the factory than they did just a few decades ago, there are still things vehicle owners can do to help fight off the effects of the elements," said Mike Stoops, a senior global product and training specialist at the car care company Meguiar's.

Here's what to do—and what not to do—to keep car-killing corrosion at bay.

Apply a Coating to the Underbody

Rust is a chemical reaction that happens when moisture and oxygen interact with the iron in steel and other metals. The process breaks down the metal as it creates iron oxide. Chips and scratches in your car's paint expose the metal underneath to the elements. Salt and other chemicals used to treat icy roads accelerate the process.

Since rust normally begins on a car's underbody parts, one of the most effective ways to protect your car is to apply a protective coating that essentially acts as a seal for the underbody—undercoating. This is especially important in so-called Rust Belt states where wet and wintry weather can brutalize cars.

"If you live in the Rust Belt, having a professionally applied undercarriage rust-proofing treatment performed as soon as possible is a good idea," Stoops said.

Several types of coating are available, including rubberized, asphalt-based, and polyurethane products. Some are relatively easy and inexpensive to apply, though they normally won't last for the life of the car, while others are more expensive but are designed to protect the underbody for many years. Coating a car's underbody can cost as much as $1,000 depending on the type of product you choose.

While adding a layer of protection works great for the undercarriage, the same doesn't apply to the body itself, Stoops notes. Waxing your car might make it look spiffy, but it won’t prevent rust.

"The paint itself is a great barrier and protector of the metal panels to which it's applied, and it is far more durable and tougher than any product you can pour out of a bottle, wipe on in a microscopically thin layer, and then wipe off the excess," Stoops said. "Waxes, synthetic sealants, and even ceramic coatings are all 'sacrificial barriers' that are designed to protect the paint in large part by taking the brunt of environmental attacks and sacrificing themselves in order to prevent paint damage."

Pressure-Wash the Underbody

If your car is covered in a thick layer of road salt, you can imagine what the underbody looks like. Even if you've treated your car's undercarriage, regular pressure-washing is still important. It will make sure salt and mud don't build up in the nooks and crannies and eventually allow rust to form.

"It's a good idea to at least forcefully rinse the undercarriage of your vehicle frequently, even when you can't give the vehicle a proper washing," Stoops said. "Use of a pressure washer, including those found at coin-operated car washes, to forcefully rinse the undercarriage, wheel wells, wheels, and body surfaces will effectively remove corrosive salt deposits that can creep into small, untreated spaces and take hold, causing rust over time."

Touch Up Those Paint Chips

Chipped paint is an open invitation to rust. You can use car wrap or paint protection film to help prevent this. Stoops recommends touching up those chips—and doing so before winter sets in to make sure salt and other chemicals don't have time to attack the exposed metal. The same applies to scratches and other types of body damage, such as deep dings and dents. Any defect that exposes the metal is a potential rust spot.

"With the adoption of galvanized steel… and other advancements in automotive manufacturing, [rust] isn't as great a concern as it used to be," Stoops said. "Something that has not changed is that exposure can lead to stone chips on the front of the vehicle. While these chips aren't a big concern for rust potential on urethane bumper covers, they certainly are when deep enough to expose metal on the hood or front of the fenders. Such deep chips should be touched up with an appropriate automotive-grade touch-up paint."

Touch-up paint is available in almost all production colors at auto parts stores or from online retailers.

Buy Rubber Floor Mats

The slush your shoes carry into the cabin can cause rust when it melts and seeps into the carpet, especially if it's loaded with salt and other chemicals. Rubber floor mats keep your car's carpet dry and clean through the winter.

Universal floor mats can be had for less than $50, but they're designed to fit a wide variety of cars and likely won’t be a perfect match for your footwells. Custom-fit floor mats will cost much more—some companies charge nearly $200 for a set of front and rear mats—but they’ll fit your car perfectly, so they won't slip around and they'll do a better job of protecting the carpet.

Store Your Car During the Winter

While it might not be the most practical option, keeping a car off the road during the winter months is the best way to keep it rust-free. This solution requires a covered parking spot and a second car to drive until spring, and it’s not as simple as just park-and-forget. You’ll need to take some precautions before you tuck your pride and joy in for hibernation.

The ideal storage location is a closed space, like a garage or a barn, but a carport will also do the trick. But first, take the car for its last drive of the year and fill up the tank to prevent moisture from building up and seals from drying out. Next, wash and wax the car, change the engine oil, add fuel stabilizer to the tank, and disconnect the battery.

Finally, remember that rodents get cold in the winter, too. They instinctively look for warm, comfortable places—like your car—to spend the season. Rodent-repelling products will help make sure your wiring, upholstery, and carpet are bite-free come spring.

Ronan Glon

Ronan Glon is an American journalist and automotive historian based in France. He enjoys working on old cars and spending time outdoors seeking out his next project car.