August 31, 2026Quebec's road salt is especially hard on a vehicle's body. Here is what you need to know about rustproofing treatments and how well they really work.
Why Quebec is especially hard on vehicles
Quebec spreads several million tonnes of road salt on its roads every year. That salt, combined with moisture and the freeze-thaw cycle (sometimes several times a week), creates an extremely corrosive environment for a vehicle's body and underbody.
The different types of rust protection
Not all treatments are equal:
- ✓Rust-inhibiting oil (underbody spray): the most effective for the underbody, it seeps into seams and cavities. Reapply every 1 to 2 years.
- ✓Wax or polymer: surface protection for painted body panels.
- ✓Electronic (electronic waves): effectiveness has not been scientifically proven.
- ✓Cavity treatment (injected into doors and rocker panels): very effective for hollow areas.
When to apply it, and how often?
The best time for a rustproofing treatment is in the fall, before the first snow and before the salt appears. For a new vehicle, do it within the first few months. For a used vehicle, have the existing rust cleaned off first, then apply the product.
- ✓New or recent vehicle: treatment within the first 6 months, then every 2 years
- ✓Vehicle more than 5 years old: yearly inspection, treatment every 1 to 2 years
- ✓After each winter: high-pressure wash of the underbody
A good habit: regular winter washes
Beyond treatments, the best protection is still to wash your vehicle regularly throughout the winter, especially the underbody. After each thaw or rain followed by a freeze, salt residue dries and its corrosive action becomes more concentrated. Washing twice a month can double the life of your underbody.
