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Reality Check: What Road Salt Is Really Doing to Your Car

South Carolina National Guard members prepare to transport road salt to affected areas in the Palmetto State.

Most of us eagerly welcome the transition from winter’s chill to spring’s warmth. As you begin tending to your garden and yard, your car will also need some tender, loving care. Road salt and other corrosive materials may be taking a silent toll on your ride — on the surface and underneath.

Road Salt, Brine and Corrosion — Oh My!

If you traveled anywhere this past winter where the roads were treated, your car may have picked up some of the residue left behind. That residue may be present even when roads are otherwise clear. It can take multiple rainstorms to wash it all away.

An assortment of chemicals may have been applied to the road, including magnesium chloride, calcium chloride, potassium acetate, calcium magnesium acetate and sodium chloride (salt). Local and state transportation departments in affected areas routinely apply a brine solution to roadways in advance of expected storms. Likely, you won’t know what exactly was applied to the roads, but these deicers have one common characteristic: They are highly corrosive to your car.

The Effect of Corrosive Materials

An iconic International pickup truck suffers from rust at the base of the liftgate.

If your car is dirty, you should either wash it yourself or bring it to a car wash. This should help to preserve your finish when followed up with a wax treatment, providing a greater level of protection.

Your car’s undercarriage is where road salt and other corrosive chemicals are slowly eating away crucial mechanisms. Chemicals that are easily washed off your car’s exterior tend to become embedded in your shock absorbers, settle on your wheel wells, invade door panels and rest in secret cavities and crevices you can only observe by placing your car on a lift.

Even worse, these chemicals are hygroscopic, meaning they attract and retain moisture. When they stow away in your undercarriage, they act as moisture magnets that slowly corrode any metal surfaces. If this is left untreated, you may face hundreds, if not thousands, of dollars in damages in coming years.

Caring For Your Car

So how should you treat your car? Simply put, you should give it a wash, but how you choose to wash it can significantly impact whether you eradicate or exacerbate your road salt problem.

Using a power wash wand to reach under your car and clean off the components may worsen the problem, for example. This method will free dirt and debris from tight spaces; however, the high pressure might also push some of the road salt deeper into those hidden crevices, enabling the corrosion to continue.

To avoid this pitfall, take your car to a brushless car wash with an undercarriage spray. The brushless wash will preserve your finish while the undercarriage spray will evenly reach every area of your car’s underside.

Bringing your vehicle to a car wash throughout the winter to prevent corrosive buildup is ideal. Regardless of your winter washing practices, you may want to return one or two more times until the last of the corrosive residue is gone from local roads.

Preserve Your Finish

Now that your car is free of road salt, it’s time to apply the first wax of the season to your ride. This is also an ideal time to inventory your personal supply of car wash materials, including mitts, tire and wheel cleaner and interior detailer.

Check out all the paint & body products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on cleaning rock salt off of your car, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Image courtesy of Wikimedia Commons

Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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