Washing your car in a Lethbridge winter

Cold water barely touches road salt. That is the whole problem with winter washing, and it is the reason AK Auto Spa heats the water and the chemicals rather than just the bay.

Salt does its damage where you cannot see it

The paint is not what you are washing for. Road salt and the brine Alberta spreads before a storm sit in the wheel arches, along the pinch welds, inside the rocker panels and all over the underside of the car — places that stay wet and never see sun. That is where rust starts, and by the time it shows on a panel it has been working for a couple of winters.

Brine is worse than rock salt for this. It is already in solution, so it creeps into seams that dry salt would fall out of, and it keeps working at temperatures where rock salt has stopped. A car that looks clean can be carrying it.

Why cold water does so little

Detergent chemistry slows down as it cools. Below freezing, cold soap is doing a fraction of the work it does in July — it hits the salt film and runs off before it has lifted anything. You end up using more product, more time and more pressure for a worse result, and blaming the wash.

Warm water and warm chemicals change that. The soap stays active long enough to break the bond between the salt film and the paint, and the high-pressure rinse then carries it away instead of pushing it around. Heated chemicals are the part most self-serve washes do not have, and in February it is the difference between a wash and an expensive rinse.

A winter order of operations

Start with the pre-soak and spend most of it low — wheel arches, rockers, behind the wheels, the front valance. Let it dwell while you do the upper panels. Then wash soap top to bottom, rinse thoroughly, and finish on the spot-free rinse so the car dries without mineral spots.

Do not skip the underside because you cannot see it. Aim the wand up into the arches and along the sills from both ends of the car. It is the least satisfying part of the wash and the only part that is actually about rust.

Not freezing your doors shut afterwards

This is the bit people learn the hard way. Water sitting in a door jamb at −20 °C turns the seal into a weld, and pulling hard on a frozen seal tears it.

Use the air setting before you leave the bay. Blow out the door jambs, the mirrors, the trunk and tailgate shuts, the fuel door and the badge recesses. Open and close each door once while you are still in the warm bay. If your locks are the keyed sort, a shot of air at the barrel is worth the ten seconds.

The heated bay and the closed door help here — the car leaves warmer and drier than it would in an open bay with a crosswind — but the air setting is what actually clears the water out.

How often, through a chinook winter

Southern Alberta thaws and refreezes more than most places, and every thaw reactivates the salt sitting in the seams. That argues for washing more often in winter than in summer — every week or two through the salted months, rather than waiting for the car to look dirty.

The bays are heated, lit and open at 3am, so the timing is yours. The cold mornings when a wash seems least appealing are exactly the ones where the salt is working hardest.

Questions people ask