Protecting Your Car from Road Salt Damage

Article overview

• How road salt works: Understand the science behind road salt and how it keeps roads safer during icy conditions.
• The hidden danger: Discover how salt can corrode your car’s undercarriage, suspension and exterior, leading to costly damage.
• Protect your vehicle: Learn practical tips like regular washing, waxing and undercoating to prevent salt damage and extend your car’s lifespan.

Winter temperatures and precipitation mean a lot of snow, sleet and ice, so in many areas around the country, roads are regularly treated with salt. While salting improves traction and reduces crashes, it can also damage the undercarriages of trucks and cars. Salt and salty slush from melted ice and snow sticks to tires and splashes onto a vehicle’s underside, which, if left untreated, can severely damage exposed parts. 

How road salt works and affects your car

Road salt, also known as rock salt, helps keep roads safe through its chemical properties. Salt lowers the freezing point of water, so when applied, it causes some of the ice to melt immediately, helping clear patches that could cause vehicles to skid or stop safely.

Rock salt is sometimes used to make homemade ice cream. The same idea applies to winter roads. When salt mixes with ice, it lowers the freezing point of water. This causes ice to melt even when the air is below freezing. On roads, melting turns slick ice into salty water that is less likely to refreeze right away.

In some areas of the country, road crews spray the asphalt with a brine mixture before precipitation begins. Rock salt can bounce or blow away, and the brine sometimes sticks to the pavement better. However, the effects are the same - corrosion.

While driving, salty water that splashes onto a vehicle and clings to metal parts underneath can accelerate rust and corrosion. The United States Environmental Protection Agency (EPA) estimates that the use of road salt has an annual impact of $5 billion on vehicles, roads and bridges in the U.S. 

Which parts of your vehicle are most at risk?

When cars and trucks travel on treated roadways, the salty slush left behind sprays up under and around the lower areas of vehicles. That undercarriage area is not only part of the vehicle's frame but also where the suspension is housed. Since it’s located underneath, there's generally no coating or paint like other parts of the vehicle.

With all the seams and small parts in the axel housings and inside of wheel wells, the risk of corrosive salt getting trapped is high. And drivers shouldn’t ignore other parts of the vehicle’s exterior either. Splash-up from the wheels, driving through puddles, or when other cars pass, can land on hoods and doors as well.

Add to that the wet nature of winter, how salt holds moisture and acts as a corrosive agent, and salted roads are a recipe for disaster if owners don’t actively work to combat winter damage.  

Protecting your engine and other mechanical features

While the engine itself is typically well-protected under the hood, there are steps you can take to safeguard it and other mechanical components from salt damage:

1. Install a splash shield or skid plate

Many vehicles come with splash shields or skid plates that protect the underside of the engine and other critical components. If your car doesn’t have one, consider installing an aftermarket shield. These barriers help prevent salty slush from splashing onto sensitive parts.

2. Regularly wash the undercarriage

Salt can accumulate on the undercarriage, where it can corrode parts like the oil pan, transmission housing and other mechanical components. Regular undercarriage washes, especially after driving on heavily salted roads, can help remove buildup before it causes damage.

3. Check and seal vulnerable areas

Inspect areas where salt might seep in, such as around gaskets, seals and wiring. Ensure these are intact and replace any that show signs of wear. Salt can corrode electrical connections, so keeping these areas sealed is essential.

By taking these steps, you can help protect your engine and other mechanical features from the corrosive effects of road salt, ensuring your vehicle stays in good condition throughout the winter.

Signs of salt damage on your car

Catching salt damage early is the best way to prevent long-term problems. Knowing what to look for helps you act quickly. Here are a few key signs that road salt is affecting your vehicle.

One of the most obvious signs is visible rust. Start by checking the areas most exposed to road spray. Look at your vehicle’s undercarriage, wheel wells and the frame. You might also spot rust forming along the edges of the doors, hood and trunk lid. These spots often begin as small bubbles under the paint before breaking through as reddish-brown patches.

Discoloration is another early warning sign. The salt and chemicals used on winter roads can be harsh on your car’s paint. You may notice dull spots or a hazy film on your vehicle’s finish, particularly on the lower sections of the body panels. This happens when the salty slush eats away at the protective clear coat.

Finally, listen to your car. While driving, pay attention to any new or unusual sounds coming from underneath the vehicle. Corrosion can affect suspension components and the exhaust system. A squeaking or creaking noise when you go over bumps could indicate that salt has damaged bushings or other moving parts.

Similarly, if the engine sounds louder than usual, it might mean rust has created a hole in the muffler or exhaust pipe. Regularly inspecting these areas and listening for changes can help you protect your car from lasting damage.

Protecting your car from road salt damage

During the winter months, one of the best ways to protect a vehicle from road salt damage is to clean it regularly. Washing a car helps remove salt before it has time to cause corrosion.

A wash that includes undercarriage cleaning is essential. There is always the option to add an aftermarket undercoating, but attention to clearing underneath the car is still important.

Even when temperatures are below freezing, car washes offer winter-safe options to help rinse away buildup. Washing a vehicle every two weeks during winter, and more often after heavy snowfall, is a good rule of thumb.

Another way to help reduce damage is to wax the entire vehicle. Wax creates a barrier on painted surfaces, making it harder for salty slush to stick. While wax does not prevent rust entirely, it can slow corrosion and makess cleaning off residue go more quickly.

Spraying off salt with plain water is a good way to limit buildup. A quick rinse after driving on heavily treated roads can reduce the amount of time salt stays on the vehicle. Parking in a garage also helps, since keeping the car dry limits the moisture that salt needs to cause corrosion.

Taking these simple steps throughout winter helps protect vehicles and extend their lifespan.