Surface Rust vs. Structural Rot: When to Walk Away
A little orange fuzz is fine. A hole in the frame is fatal. Learn how to tell the difference with a simple screwdriver test.
Quick Answer
Rust is "auto cancer."
* Surface Rust (Manageable): Light orange dusting on heavy suspension parts. Safe to buy, but treat it.
* Structural Rot (Fatal): Flaking metal, holes, or "crunchy" sounds when tapped. Do not buy.
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The Danger Zones
Don't look at the hood. Look where it matters.
* Rocker Panels: The metal strip below the doors. This is structurally vital for side-impact protection. If it's bubbling, the safety cage is compromised.
* Subframe Mounting Points: Look where the engine/suspension bolts to the body. If the metal around the bolt is thinning, the engine could literally fall out.
* Brake Lines: Follow the metal tubes underneath. If they look like crusty worms, they will burst under hard braking.
The Screwdriver Test (Discreetly)
Sellers hate this, but it saves your life.
* The Technique: Take a key or a small screwdriver. Poke the rusty spot on the frame rail (under the car).
* Solid Thud: It's just surface rust. Safe.
* Crunch/Penetration: If the tool pokes through or the metal flakes off in chunks, the car is structurally totaled.
Why Geography Matters
* The "Salt Belt": Cars from the Northeast/Midwest US use road salt. 10-year-old cars here often have frame damage.
* Coastal Cars: Ocean spray eats roofs and hoods (top-down rust).
* Title Washing: Beware of cars from snowy states being sold in the South.
Summary
Surface rust is a bargaining chip (ask for $500 off). Structural rot is a death sentence.
> Know the Origin
> MotorMigo helps you check the history to see if the car spent time in "Salt Belt" states like Michigan or New York, alerting you to check for hidden underbody rust.
Use a guided inspection before you commit
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