How often to wash your car in winter

A base interval

Salt season around London usually runs from the first real snow in late November or December until the roads stay clean in late March or April. Through that stretch, a wash every seven to fourteen days keeps salt from sitting on the car long enough to do much harm. If you drive a lot, park outside, or keep a car you plan to own for many years, lean toward weekly.

When to go sooner

Some weeks put far more salt on a car than others. These are the ones worth an extra wash.

• After a storm, once the plows have been through and the roads are salted and wet
• After a thaw, when the roads turn grey and every passing car sprays you
• After a long run on the 401 or 402, where traffic throws brine up at highway speed
• When white streaks show on the lower doors and the rear bumper
• Before leaving the car parked for a week or more, for example at the airport
• After lake-effect squalls coming in off Lake Huron, which can mean several salting rounds in a single day

Picking the day

The best winter washing days are near or above freezing, in the middle of the day. A sunny afternoon at minus two is far better than a windy evening at minus eighteen. Water has time to run off and the door seals have a chance to dry before night.

If a deep cold spell lasts more than a week, still wash. Salt keeps working at low temperatures, just more slowly, and it will be waiting when the next thaw arrives. Just give yourself a few minutes afterwards to deal with seals and locks.

After a wash in the cold

Most winter wash complaints, like doors frozen shut or wipers stuck to the glass, come from leftover water. A short routine before you drive off prevents them.

• Open each door and wipe the rubber seals and the bottom edge with a towel.
• Do the same for the trunk or hatch seal and the fuel door.
• Work flush or pop-out door handles a few times so they do not freeze in place.
• Check the wipers are free of the glass before switching them on.
• Press the brakes gently a few times in the first block to dry the pads and rotors.

Underneath matters more than shine

In winter a clean-looking car is not the goal. The brake lines, subframe and rockers are what salt damages, and those are what you want rinsed. A wash that only sprays the paint leaves most of the salt where it was. At Fast Lane, the Full and Luxury washes include an under-car spray, and since the bay is open 24 hours, you can go on the mild afternoon or late evening that suits you.