The honest answer: it depends on where you drive, how you use the car, and the season. A useful baseline for most Montréal drivers is a full detail two to four times a year, with lighter maintenance in between. Here is how to think about it rather than just picking a number.
Exterior cadence. For a car that lives outside, a thorough exterior detail every three to four months keeps contamination from setting into the paint. The two hinge points in Québec are winter and spring. Road salt and calcium sprayed across the island through the cold months are corrosive, and they collect in wheel wells, rocker panels, and under the bumpers where you never look. A February wash that skips the undercarriage does almost nothing. Then in April, once the salt trucks stop, book a proper spring decontamination to strip what winter left behind. See [remove-road-salt] for why this matters more here than almost anywhere else, and [clay-bar] for how bonded grime gets removed.
Interior cadence. Interiors run on a different clock, driven by traffic not weather. If you commute daily, eat in the car, or carry kids or a dog, a full interior detail every three months is reasonable, with a quick vacuum and wipe-down monthly. Winter is brutal on interiors too: salt and slush tracked onto floor mats will stain carpet and etch rubber if left. A light-use weekend car can stretch interior detailing to twice a year.
Adjust for reality. Garage-kept, low-mileage, mostly highway? You can lean toward the twice-a-year end. Street-parked downtown, high mileage, or a work vehicle? Push toward quarterly or more. If you have [ceramic-coating] on the paint, exterior maintenance gets easier and less frequent, though it does not replace washing.
The goal is not a rigid schedule. It is catching salt, sap, bird droppings, and embedded dirt before they cause permanent damage, which is always cheaper than correcting it later. If you would rather not track this yourself, LuxWash is a platform that connects you with vetted car care pros who come to you, coming first to Montréal. You can [join the early-access waitlist]. For a sense of what a session covers, read [full-detail-included], and for pricing, [mobile-detailing-cost-montreal].