Behind the Wheel

Road Salt Damage: Your Car’s Corrosive Nightmare

December 29, 2019
Every winter, our quaint, Midwestern town of Kansas City spends $20 million and employs anywhere from 100 to 200 salt trucks to de-ice the roads. That’s a lot of dough and hard work to ensure we commuters can drive safely. Yet, as necessary as road salt is for drivers’ safety, it’s a certifiable, rust-raving catastrophe for vehicles. Short of becoming a hermit or moving to a warmer area, you can’t avoid road salt—but you can reduce the chances of it damaging your car.

Why does road salt damage vehicles?

It’s all science, really.

Road salt—typically sodium chloride—mixes with ice—solid dihydrogen monoxide—to lower the molecules’ freezing point and melt ice and snow. But as sodium and chlorine ions disengage to do their oxidation jobs, they become food for metals, particularly iron and steel. The addition of free hydrogen molecules, as well as other chemicals, only increases the corrosive effect road salt has on a vehicle’s frame.

Once corrosion and rust take hold, it spreads around your vehicle quite quickly. So, unless you drive a car made of solid gold—gold is immune to oxidation—then you should probably clean the road salt off right away.

If I don’t see rust, should I still worry?

Rust is a fickle beast. Just because you don’t see it munching on your car, doesn’t mean it isn’t hiding in the shadows. The road salt and snowmelt can find a cozy home underneath your vehicle for days, weeks even, and won’t necessarily show signs of visible damage after being cleaned off. If you drive on a salted road, don’t trust your eyes—trust science, and go get your car washed.

What types of vehicle damage can road salt cause?

Rust or corrosion caused by road salt can do a number on more than just your vehicle’s frame. For example, road salt can cause hydraulic brake or fuel line leaks. Or, it can corrode coil springs, exhaust and mufflers, brake rotors, axles and more. If you have any chipped paint or dents, road salt can sneak in there and begin to nibble away, so it’s important to visit a trusted autobody shop for repairs prior to winter.


How often should I wash my car in the winter?

After a snowstorm and the last of the salting trucks goes through, it’s a good idea to get a thorough cleaning of your vehicle and, most importantly, its undercarriage. The quicker you get the car cleaned, the better, so don’t hesitate to visit the car wash multiple times after a snowfall. If you’d like to take a more conservative approach to cleaning road salt off your car, opt for a full wash every month.

While I generally approve and suggest hand washing your car, that’s not always a practical solution during Kansas City’s chilliest months. So, off to your local carwash you go! (Consider buying a monthly membership to get unlimited vehicle undercarriage cleanings through winter.)

Read more car washing tips. What can I do to prevent road salt damage? Your vehicle is going to battle road salt; what’s important is what you do to help it win that fight. Here’s some advice to help you both out:
  • Wax your vehicle in the spring and fall. Apply a hardy sealant over the wax, too, for even more protection.
  • Fix your seemingly cosmetic dents, dings, chips and cracks by going to a body shop.
  • Avoid driving the day (or two) after a snowstorm to avoid salted roads.
  • Get an undercarriage oil-based pre-treatment, or maybe opt for a fluid film, polyurethane or rubberized undercoating.
  • Wrap your car in a vinyl coating for invisible protection.
  • If you have an older car, consider trading it in for a newer vehicle that’s been rust-proofed.
  • Avoid deep snow, particularly snow that’s been plowed, as these snowbanks can have an overabundance of road salt.
  • Get a pre-winter inspection at your local auto service center; this will help you identify potential problem areas before they arise.
Road salt: We love you, but we also can’t stand you. Why can’t you just let us be happy?

For more help getting over the winter blues, follow my other tips to protect your car from the outside elements.


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