The honest answer is every two weeks for most drivers. But the weather, where you park and what you drive through all shift that number.
Winter: every 7 to 10 days
Road salt and brine eat at brake lines, wheel arches and lower panels. Wash more often, and always ask for an underbody rinse.
Spring: every 2 weeks
Pollen and tree sap are acidic and bake into paint on the first warm days. Do not leave them sitting for a month.
Summer: every 2 weeks, sooner after road trips
Bug splatter and bird droppings can etch clear coat in a few days of hot sun. Remove them quickly, even if the rest of the car can wait.
Fall: every 2 to 3 weeks
Wet leaves stain paint and block drain channels. A wash before winter is also the perfect time for a coat of wax.
