How to Clean and Maintain Your Vehicle’s Undercarriage

Most drivers understand the importance of washing a vehicle’s exterior. But overlooking its underside can be a costly mistake due to road salt and sand and the freeze-thaw cycles that come with Alberta’s winters.

Road salt and de-icing treatments are important for road safety, but they are highly corrosive to your vehicle’s metal parts. On top of this, temperature fluctuations cause moisture to expand inside tiny surface imperfections, potentially cracking protective sealants. This can allow rust to creep in. Further complicating matters is the fact that, unlike your car’s painted surfaces, you can’t spot rust or corrosion developing on the frame, exhaust, brake lines, fuel lines, wheel wells and suspension without getting under your vehicle for a closer look — a task best left to your mechanic.

Here’s how to take care of what lies beneath.

First, have your vehicle treated with an anti-rust undercarriage coating — a solvent-free petroleum-based formulation — either by your local auto shop or a specialist. In Alberta, where many cities use a sand-and-gravel mixture (pickle mix) with a small total salt content, treating every year or two is fine. Treat your new vehicle right away, before it has its first encounter with sand and salt.

The second thing to do is to thoroughly wash your car’s underside every two weeks or so, either at a professional car wash or a do-it-yourself facility. (AMA members save 10% on car washes at Shell.) If you choose a commercial car wash, select a touchless one that includes an undercarriage spray. The goal is to remove as much salt and sand as possible. In winter, try to wash your car on warmer days so components like brake lines do not freeze.

All of this may seem like a hassle, but it’s a relative bargain compared to the potential ravages — to your car and your wallet — of unchecked rust. Your vehicle will look great, too. AMA