Winter Prep Salt and brine season is coming — seal your undercarriage before the first application. Book now →

Coeur d'Alene Airport · KCOE · Hayden, Idaho

Undercoating and Rust Protection for Spokane and North Idaho

DINITROL · KSL Ceramic · Cavity Injection

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Why It Matters Here

North Idaho Winters

A note on North Idaho winters Idaho and Washington both run salt and magnesium chloride brine on the highways through the winter. Brine is worse than rock salt for a chassis — it stays wet longer, creeps into seams and cavities, and keeps working long after the road is dry. If your car sees any winter miles at all, cleaning the undercarriage and then sealing it is the single highest-value thing you can do for it. Come in before the first application goes down, not after.

Two Approaches

Coating Options

Corrosion protection for vehicles driven through Spokane, North Idaho, and Eastern Washington winters. Both options start the same way — a dry ice–cleaned chassis, so the coating bonds to clean metal instead of sealing grime underneath it. Which one is right depends on the car and how you use it.

DINITROL Undercoating

Corrosion protection for vehicles that live where the roads get salted. We apply DINITROL 4941 underbody coating in black or clear, plus DINITROL ML and 1000 cavity waxes injected into rocker panels, frame rails, doors, and box sections — the places rust starts where you can't see it. Applied over a dry ice–cleaned chassis, so the coating bonds to clean metal instead of sealing grime underneath it.

KSL Ceramic Coating

Supplier and installer of KSL Ceramic undercarriage coating, applied in-house at the hangar. Protects chassis, floor pans, and suspension components against road salt, moisture, and debris — for classics, performance vehicles, and daily drivers alike. The ceramic option when you want a harder-wearing surface finish than a wax-based undercoat.

How we clean it first →

Featured Work

Hummer H2

Undercarriage dry ice cleaned, then sealed with DINITROL 4941 underbody coating. Each area photographed at every stage from the same angle — the actual truck, not a stock photo.

Hummer H2 rear wheel well before cleaning, with rust scale and road grime on the frame rail, trailing arm and shock mount Before
The same rear wheel well after dry ice cleaning, grime and loose scale removed down to the metal Dry Ice Cleaned
The same rear wheel well after undercoating, frame rail and suspension sealed in black DINITROL 4941 Undercoated
Rear Wheel Well · Before / Dry Ice Cleaned / Undercoated
Hummer H2 front wheel well before cleaning, with rust-scaled frame rail and control arm Before
The same front wheel well after dry ice cleaning, grime and loose scale removed down to the metal Dry Ice Cleaned
The same front wheel well after undercoating, frame rail and control arms sealed in black DINITROL 4941 Undercoated
Front Wheel Well · Before / Dry Ice Cleaned / Undercoated

The middle frame is the dry ice step. Grease, road film and loose scale are gone, and what’s left is the sound metal underneath — surface rust included. That’s the point of cleaning first: the coating bonds to clean metal instead of sealing grime underneath it.

Hummer H2 frame rails and transmission crossmember before cleaning, covered in rust and road grime Before
The same frame rails and crossmember after dry ice cleaning and undercoating After
Frame & Transmission Crossmember
Hummer H2 rear axle, hitch and rear frame section before cleaning Before
The same rear axle, hitch and frame section after dry ice cleaning and undercoating After
Rear Axle & Hitch
Hummer H2 frame rails alongside the fuel tank and muffler before cleaning Before
The same frame rails alongside the fuel tank and muffler after dry ice cleaning and undercoating After
Frame Rails · Fuel Tank & Muffler

Common Questions

Undercoating FAQ

When should I get undercoating done?

Before the first brine application goes down, not after. Idaho and Washington both start treating highways as soon as the weather turns, and once salt is in the seams you're sealing over contamination instead of clean metal. Fall is the right window. If you've already driven a salted winter, we clean first and then coat.

Will undercoating trap rust that's already there?

Not the way we do it. The chassis gets dry ice cleaned first, so the coating bonds to sound metal instead of sealing grime and salt underneath it. Coating over dirty steel is how undercoating got its bad reputation. If there's genuine rot rather than surface rust, you need metalwork before any coating goes on, and we'll tell you that up front.

My vehicle already has undercoating on it. Can you go over it?

No, and you wouldn't want us to. Old undercoating has to come off, especially anything loose or flaking — coating over it just seals the failure in and traps moisture underneath. Dry ice cleaning handles this, and it can strip the original coating completely, which is what we prefer. Starting from bare, sound metal is the whole point.

Do you treat inside the frame rails and rocker panels?

Yes. DINITROL ML and 1000 are cavity waxes, injected into rocker panels, frame rails, doors, and box sections. That's where rust actually starts — from the inside out, where you can't see it. Underbody coating alone leaves those cavities untreated.

Can you coat a brand-new vehicle?

That's the best case — no existing corrosion, and protection goes on before the first winter instead of after several. It still gets a dry ice clean first. New undersides aren't clean undersides; there's grease, road grime from transport, and manufacturing residue on them, and coating over any of that means the coating bonds to the residue instead of the metal.

Black or clear — which should I pick?

Black is the standard choice and what most vehicles get. Clear is for when you want to keep the original look of the underside visible — an original-paint car, a collector vehicle where the factory finish matters, anything where you'd rather see what's under there than cover it.

How long will my vehicle be at the shop?

Plan on up to a week. That covers prep, cleaning, application, and curing time between coats. It isn't a same-day service, and anyone offering it as one is skipping steps.

What is the difference between undercoating and ceramic coating?

DINITROL is a wax-based corrosion barrier. It stays flexible, tolerates flex and impact, and gets injected into the closed cavities where rust actually starts. KSL Ceramic is a harder-wearing surface coating for chassis and underbody. They solve overlapping problems in different ways, and the right answer depends on the car and how you use it. Ask and we will walk you through it.

Contact

Phone

208-929-5058

Location

Coeur d'Alene Airport (KCOE)
Hayden, Idaho

Service Area

North Idaho · Spokane
Eastern Washington · Western Montana

Messages go straight to the shop — we reply within one business day.