Why Washing Your Car in Winter Matters

Washing your car in winter matters because road salt and liquid de-icers cling to the underside and speed up rust, often where you can’t see it. A regular wash is cheap next to the brake, fuel and exhaust repairs that corrosion can lead to.

It can feel pointless to wash a car that’ll be filthy again by tomorrow. But the goal in winter isn’t a shiny car. It’s getting salt off the metal.

What salt does to a car

AAA says rock salt and liquid de-icers can rust and corrode vehicle parts, and that it goes well beyond looks. The damage can reach the brakes, fuel tank and exhaust system.

People who fix cars for a living describe the same thing. A Minneapolis body shop owner told WCCO in 2015 that brake lines are typically where the problems start. A Massachusetts shop owner told Western Mass News in 2026 that an outer panel can look fine, with just a small hole showing, while the inside is already badly corroded.

There’s one more reason to stay ahead of it. AAA says corrosion usually isn’t covered by insurance.

What it can cost

AAA’s most detailed numbers come from a 2016 survey of 1,001 U.S. drivers.

• 70 percent of drivers lived in a winter climate region, either then or in the previous five years.
• 15 percent of those drivers had needed a repair for salt-related rust in the past five years.
• The average repair cost $490.
• The total came to an estimated $15.4 billion over five years, or more than $3 billion a year.

Those figures are about a decade old, so today’s repair bills may be different. They still make the point: a wash costs far less than a brake line.

How often to wash in winter

Advice varies, so match it to your roads.

Who said it	Advice
AAA, February 2026 release	At least about every two weeks, sooner after heavily salted roads
AAA, as reported by News 12 in 2026	After each winter storm
Minneapolis body shop owner, 2015	Once a week
Consumer Reports’ Jon Linkov, 2018	An undercarriage wash about once a season, not on every visit

If your roads are treated all winter, every two weeks is a solid baseline. Add an extra wash after a big storm when the weather allows. If you only see salt a few times a year, you can relax a little. For the rest of the year, see how often you should wash your car.

What to focus on

The underside. This is the priority. AAA suggests using car washes with underbody sprays to reach the chassis, and flushing loose salt off before a full wash to protect the paint.

Wheel wells and lower panels. Road spray collects here, so give them extra time.

The right soap. AAA says to use a detergent made for vehicles. It warns that household dish detergent strips wax, which is the last thing you want in salt season. Here’s more on why dish soap is a bad idea.

Washing the underside at home is harder than it sounds. Runoff from oily parts is a concern too, and Portland, Oregon, tells residents never to wash undercarriages at home. And never get under a car held only by a jack. For most people, a commercial wash with an underbody spray is the safer and easier choice. If you’re choosing between types, compare touchless and soft-touch washes.

Get ready before the salt arrives

AAA’s pre-winter steps take one good weekend.

1. Wash and clean the car thoroughly.
2. Repair body damage.
3. Touch up chips and scratches where bare metal shows.
4. Apply a good coat of wax. The waxing guide has the steps.

Put these on your seasonal car care checklist so they happen before the first storm.

Washing in the cold without freezing your doors

Cold weather brings its own problem: water that freezes in door seals and locks. Stoner Car Care, which sells detailing products, offers some sensible tips.

• Wash during the warmest part of the day, typically early afternoon.
• If you’re hand washing, use mildly warm water, not hot or icy water.
• Apply a silicone spray to door seals before you wash.
• Dry the car completely, with extra attention on door jambs, locks and seals.

If it’s well below freezing and staying there, it’s fine to wait for a milder day or use a wash with blowers. If a door does freeze shut, don’t force it. You can damage the seal or the handle.

If you drive an EV

Going electric doesn’t get you out of this. AAA’s 2026 release says EV batteries, cooling lines and electronics sit low and can be more sensitive to corrosion, and that charging ports and aluminum battery housings can degrade faster. It suggests spraying off the underside often and keeping charging ports dry and salt-free.

Check your owner’s manual for wash guidance, and if you use a pressure washer, keep it away from charge ports, seals and electronics.

Don’t stop when the snow does

Salt doesn’t leave with the snow. AAA says to give the undercarriage one last cleaning in spring, because deposits left over from winter can keep causing corrosion all year. Consumer Reports’ Linkov also points to a post-winter undercarriage wash as the one to pay for.

Warning signs you shouldn’t ignore

AAA urges drivers to move off the road to a safe place and have the car towed if they notice any of these:

• Dash warning lights for brakes or other critical systems
• A spongy or soft brake pedal
• The smell of fuel or other fumes

If you have nowhere to wash in winter, you can find a nearby car wash with an underbody option in the directory.