"Wash it every two weeks" is a common rule of thumb, but it's a starting point, not a real answer — how often a car actually needs washing and waxing depends heavily on climate, how it's stored, and what it's exposed to day to day.
What actually accelerates the need to wash
- Road salt in winter climates — it's genuinely corrosive to paint and undercarriage components the longer it sits.
- Tree sap, bird droppings, and pollen — all mildly acidic and capable of etching clear coat if left for weeks.
- Coastal salt air, which accelerates corrosion even without direct road exposure.
- Regular exposure to direct sun, which breaks down wax protection faster than a garage-kept car.
A more realistic frequency guide
A garage-kept car in a mild, dry climate can often go three to four weeks between washes without real harm. A car parked outside in a harsh winter climate, exposed to road salt regularly, benefits from washing — including the undercarriage — closer to every one to two weeks during the worst months, specifically to limit corrosion, not just for appearance.
Waxing is a separate schedule from washing
Traditional wax typically lasts somewhere in the range of four to eight weeks before it stops meaningfully protecting the paint, even if the car still looks glossy. Sealants can last a few months, and ceramic coatings — a different category entirely — are designed to last a year or more. If you're not sure which one you have, ask whoever last detailed the car.
The honest signal that it's time is less about a calendar date and more about whether water still beads and rolls off the paint when it rains — once it stops beading and starts sheeting flat, the protective layer is largely gone.