Rust is caused by moisture and oxygen reacting with steel, accelerated by salt.
Modern cars are better protected, but chips and scratches expose metal.
Prevention
- ▸Wash regularly, especially underneath
- ▸Fix paint chips promptly
- ▸Keep drain holes clear
- ▸Apply underbody protection in harsh climates
Spotting early rust
Look for bubbling paint around wheel arches, sills, and door edges.
Treatment
Surface rust can be sanded and treated. Rust that has gone through metal needs professional repair.
Storage
Store cars in dry, ventilated spaces. A damp garage can be worse than outdoors.
Buying a used car? Check for rust
When viewing a used car, check the sills, wheel arches, bottoms of doors, boot floor under the carpet, and the underside if you can. Press gently around bubbled paint — soft or crunchy metal is a bad sign. Structural rust near suspension mounts or subframes can make a car unsafe and may fail an inspection.
Surface rust on exhaust components and brake discs is normal, but heavy corrosion on brake lines and fuel lines is serious. If in doubt, pay for an independent inspection.
CAUTION: This is general automotive information, not professional mechanical advice. Always follow your vehicle manufacturer’s specifications and service schedule, and have brakes, steering, tyres, and other safety-critical systems inspected by a qualified mechanic.