5 Biggest Underside Killers
- Chassis Clean
- Jan 7
- 2 min read
Your Car's Underside Takes
The Most Abuse.
And Most of it Happens
Out of Sight.
Road Salt
Salt is one of the worst enemies of your car’s underside.
Every winter, thousands of tonnes of it are spread on Scottish roads — and it doesn’t just wash away when the snow melts.
It clings to metal, absorbs moisture from the air, and speeds up corrosion dramatically.
Over time, it eats into suspension components, subframes, and brake lines.
If you spot white, powdery residue under your car, that’s road salt — and it’s already doing damage.
Regular cleaning or dry ice blasting can stop that corrosion before it takes hold.
Old Coatings
Many cars have previously been coated with thick black “underseal” for protection — but over time, that can do more harm than good.
Once it starts to crack, peel, or lift, moisture and salt creep in underneath where you can’t see them.
The result? Rust spreads unseen until it breaks through the coating completely.
Old coatings often hide serious corrosion, especially around seams and welds.
That’s why we strip it all back first — removing every loose layer before applying modern, breathable protection that seals properly.
Trapped Moisture
Moisture is unavoidable — but if it stays trapped, it becomes a rust factory.
Mud, dirt, and grime cling to the underside, holding onto water long after the roads are dry.
Wheel arches, seams, and boxed sections are common traps for damp.
Even parking a car in a garage without drying it off can cause corrosion over time.
A deep clean or dry ice blast clears out every bit of residue, leaving bare metal that can dry properly and be safely recoated.
Oil & Grime Build-Up
Leaking oil on its own can actually slow corrosion — but once it mixes with road dirt, salt, and moisture, it turns into a thick, sticky layer that traps everything against the metal.
Moisture. Salt. Grit
It hides corrosion starting underneath and makes future cleaning and coating harder.
Left untreated, that oily grime can even soften older coatings and make them peel.
Fixing leaks early — and giving the underside a proper clean — prevents long-term damage and keeps the metal sound.
Poor Drainage
Modern cars have drain holes and channels designed to let water escape — but they don’t stay clear forever.
Leaves, mud, and undertray build-up block drainage, letting water pool in hidden corners.
This is especially common around wheel arches, sills, and subframes.
That standing water can rust through panels and welds from the inside out.
During inspections we check drain access where possible and advise on clearing or repairs to prevent long-term rust.
The Solution
Every one of these problems can be fixed — and prevented — with the right process.
We start by stripping dirt, coatings, and corrosion using dry ice, vapour, or media blasting.
Then we apply new protection: primers, rust inhibitors, stonechip coatings, and Lanoguard.
It’s not just cleaning — it’s preservation.
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