How often to wash a car in this climate
Almost every answer to this question was written somewhere with a winter. It talks about road salt, pollen and rust, and it lands on a fortnight. The fortnight is a reasonable starting point. The reasons behind it are not ours.
What moves the interval here is rain that leaves minerals rather than washing them away, ash that behaves like sandpaper, salt air that reaches a long way inland, and sun that works on the clear coat every month of the year. So the useful answer is not a number. It is where the car sleeps.
Start with where the car is parked
- Parked outdoors, driven daily every 1 to 2 weeks
- The default for most cars here. Dust from the road, exhaust film and whatever the weather adds sit on the clear coat and hold moisture against it. Two weeks is the point at which the film stops rinsing off and starts needing a wash to shift.
- Parked under trees by the event, not the calendar
- Sap and bird droppings are acidic and start etching the clear coat while they dry, so the interval that matters is hours rather than weeks. Get those off the day they land. The rest of the car can keep to the normal fortnight.
- Near the coast weekly
- Salt carries inland on the wind well beyond the last row of houses, and it draws moisture out of the air onto the panel and into every seam and bolt. A plain rinse between washes carries it off before it can settle, and it matters more underneath the car than on top of it.
- After ashfall as soon as you can, and wet
- Volcanic ash is abrasive. It is ground glass, and wiping a dusty panel dry drags it across the paint and leaves exactly the swirl marks a wash is supposed to prevent. Flood it off with water first and do not touch the panel until the ash has floated away.
- Through the rainy months the same, or slightly more often
- Rain is not a wash. It arrives with whatever is in the air, dries on the panel and leaves the minerals behind as spots, and a car that sits wet under a tree grows the marks fastest. The instinct to wash less because it keeps raining is the one that costs paint.
- Garaged, or driven at weekends every 3 to 4 weeks
- Less exposure, longer interval. Dust still settles indoors and still scratches if it is wiped dry, so the wash matters even on a car that has barely moved.
- Waxed or sealed stretches the interval
- Wax gives dirt less to hold on to, so more of it leaves with the rinse and the paint spends less time under a film. It does not replace the wash. It buys the paint time between them.
- Three cases have a number
- Coast, open air, and garaged. Those are the only ones a calendar helps with, and the gap between the shortest and the longest is about four times.
- Two have a trigger instead
- Sap, droppings and volcanic ash start working the hour they land, so the answer is the same day whatever the calendar says. They sit off the scale because putting them on it would be the wrong kind of answer.
- And two only move the others
- Wax stretches whichever interval you are on. The rainy months shorten it, which is the opposite of what most people do with them.
What leaving it actually does
A missed wash is not a missed wash. Water spots etch, droppings crater, and the film that holds moisture against the paint is the same film that dulls it. Every one of those is harder and slower to undo than the wash that would have prevented it, and some of it does not come back at all.
The marks it leaves, and which of them polish out, are set out on what is on your paint.
If you are not sure which case your car is in, send us a text and say where it parks. We come to the car, so the answer usually starts there anyway.
The work this describes
- Home Service Car Wash the regular one
- Interior & Exterior Detailing when it has been left