Why October Is the Time to Get Ahead of Road Salt

The salt trucks will be out on Route 2 and I-90 before long, and they won't be done until spring. Every spring, cars come into our shops with road salt damage in the same places: bubbling paint along the bottom of a door, a rocker panel that's turned orange, a wheel arch that's started to flake. Most of it started months earlier, the first time salty slush found a spot of bare metal.

October is the best time to get ahead of it. Here's what road salt actually does to a car, where it does it, and what's worth doing before the first storm.

How Road Salt Causes Rust

Rust needs three things: bare metal, water, and oxygen. Salt doesn't add a new ingredient. It makes the water on your car far better at carrying the electrical charge that corrosion runs on, so the reaction moves faster. A few months of slush gives it all the time it needs.

The way roads are treated has changed, too. Many crews now spray liquid brine on the pavement before a storm, and AAA notes that brine tends to stay on the road better than rock salt, which can bounce or blow away. Tires throw that brine up into seams, crevices, and the underside of the car.

Temperature matters more than people expect. Corrosion moves faster when it's warmer and wet, so the slushy 35-degree days do more harm than the bitter cold ones. A heated garage melts the slush off, but it can also keep salty water warm and sitting against the metal overnight, so rinsing more often matters if you park in one.

Where Rust Starts on Northeast Ohio Cars

Rust almost never starts in the middle of a clean panel. It starts where the paint is already broken, or where salty water collects and sits:

• Rock chips on the hood, the front edge of the roof, and the lower panels behind the wheels.
• Rocker panels and the bottoms of the doors, which take a steady spray of slush from the tires.
• Wheel wells and the lip of the fender arch, where wet salt collects and dries over and over.
• Folded seams, like the bottom edge of a door or tailgate, where water can sit inside the fold.
• Underneath the car: brake lines, fuel lines, exhaust parts, and the frame. Have a mechanic check those, because rust there is a safety issue, not a cosmetic one.

Much of the rust on a body panel also starts on the inside and works its way out. By the time a bubble shows through the paint, it has usually been growing for a while.

What Actually Slows It Down

None of this is complicated. What matters is doing it all winter, not once in the spring.

• Keep washing the car through the winter, including the underside. A wash with an undercarriage spray every week or two during heavy salt, and after storms once the roads dry, does more good than a spotless car in October. Milder days are the best time.
• Fix rock chips now. A chip sealed with touch-up paint before the first storm is a five-minute job. The same chip after a winter of salt can be a refinishing job.
• Put wax or a paint sealant on this fall. It won't stop a rock, but it helps salt and grime rinse off instead of bonding to the paint.
• Keep the drain holes clear. Doors and rocker panels have small drain holes along the bottom, and if they clog, water sits inside the panel all winter.
• Don't ignore a bubble. A small blister in the paint usually means rust is already working underneath it.

What About a Rhino Bed Liner?

If you drive a pickup, the bed takes its own beating in winter. Shovels, salt bags, and gear scratch through the paint, and wet salt settles into those scratches. A spray-on bed liner seals the bed floor and walls so salt and water can't reach bare metal. D&S sprays Rhino Linings in truck beds.

A bed liner is for the bed only. It isn't a coating for rocker panels or the rest of the body, and it won't reverse rust that has already started, so the bed needs to be in sound condition first. For the body itself, the washing, chip repair, and sealant habits above are what actually protect it. Our Rhino Linings FAQ covers bed liners in more detail.

When Rust Is Still Fixable

How big a repair rust needs depends almost entirely on how early it's caught. Body shops generally think about it in three stages.

1. Surface rust

Surface rust looks like orange spots or a light film, often around a chip or scratch. The metal underneath is still solid, and it can usually be sanded out, treated, primed, and refinished.

2. Scale

Scale is when the paint bubbles or flakes and the metal underneath has started to pit. The damaged area has to be cleaned back to sound metal, and it's almost always wider than it looks from outside.

3. Perforation

Perforation means the rust has eaten through and there's a hole. At that point the damaged section of the panel usually has to be cut out and replaced.

The distance between the first stage and the last is often a couple of winters. A coin-sized spot in March can be a much bigger job by the following spring.

If you're already seeing orange spots or bubbling paint, have it looked at before the salt season starts. Send us photos through our mobile repair estimate, or stop by any of our six collision centers. You'll find them all on our locations page.