Is It Dangerous to Drive a Rusty Car?

If rust is left untreated it can destroy the structure of your car, making it unsafe to drive.
Written by Alexandra Maloney
Reviewed by Kathleen Flear
Mar 9, 2022
closeup of the front of a rusty car
Whether you’ve owned one yourself, or have just seen one on the road, we all know what a rusty car looks like as it drives by. While rust can be visually unappealing, that isn’t the worst part of a rusty car. In fact, rust forming on your car can make it dangerous to drive and cause future headaches.
Here, we’re going over how rust forms on a car, when a rusty car becomes dangerous to drive, and tips for
preventing
and
repairing
rust, so you can be prepared if you ever find yourself in a rusty situation. 

How does rust form on a car?

According to
Popular Mechanics
, rust forms as a result of the electrochemical breakdown of the iron based metals in your car. When the iron surface molecules in your car interact with outside oxygen, it forms iron oxide, also known as rust.
Factors such as thickness of steel, environment, and alloy will all contribute to how quickly and severely rust forms on a car. These are the different levels of rust your car might face:
  • Surface rust: Forms on the surface of your car and is easily treatable. 
  • Scale rust: When rust penetrates deeper than the car surface, usually forming bubbles and surface that is rough to the touch.
  • Penetrating rust: If surface and scale rust are left untreated, the rust goes even deeper into the car’s surface and eventually forms holes in the exterior. 

Can car rust be prevented? 

Luckily, preventing all three kinds of rust and avoiding these problems altogether is manageable. The easiest way to prevent rust is by washing your car on a regular basis to get rid of dirt and grime. It’s especially important to wash the underside of your car, specifically if you’ve been driving on dirt or salted roads.
Keeping your car dry after it’s been exposed to water can also help prevent rust, and taking your car for regular maintenance can let professionals prevent or catch rust formation early. It’s crucial for drivers to do everything they can to prevent rust from forming on their car, because in the event rust does form, fixing
it’s unlikely to be covered by your car insurance

Is it dangerous to drive a rusty car?

While small amounts of surface rust don’t make a car dangerous to drive, if a rust problem is left untreated a huge issue will likely form. According to
NAPA
, when rust is in the surface stage, safety isn’t compromised, but as soon as it turns structural, your car becomes dangerous to drive
As soon as rust becomes scale or penetrating rust, the damage to your car is considered structural. It’s crucial to keep the structure of your car intact in order to drive it safely. If structure is compromised, inner components of your car might not work, and it could cause car accidents. 

How to fix a rusty car

If you notice rust on your car, the best thing to do is fix the problem as soon as possible.
Repair Smith
reports that once rust is in your car, the only way to stop it from spreading, and spreading fast, is to remove it completely.
To repair surface rust, start by sanding down the rusty area until you can see the exposed metal of your car. Then, apply a rust inhibitor and two layers of a rust converter. Prime if you can, then leave your car for 24 hours before you paint over the area.
For scale rust, you’ll need to get into the depths of your car’s structure. This usually involves using a wire brush to get through the rust, then using a grinding wheel and sandpaper to even out the surface. After this, you should see bare metal and can then use rust treatments.
Penetrating rust, the most severe form of rust, is typically handled best by a professional. If rust has reached all the way down to your car’s structure, ask a professional if your car is salvageable and can be safely driven again.
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