Los Angeles is a desert. This should come as news to no one, but it bears repeating. The sun burns hot, salt rides in the wind, and, these days, a thin curtain of smog hangs above the city’s highways. These things can be hard on humans, but they’re even more brutal on the cars we drive. Fortunately, in Los Angeles, “Car Wash” signs are as common a sight as palm trees. But how often do you actually need to wash your car? We’ve singled out three common assailants—sun, salt, and smog—and the solutions for each.

The Problem: Sun

The Solution: A clear-coat repair.

Just as it does to skin, the sun can blister and crack a car’s clear coat, causing damage to paint, rubber, or plastic. A good car cover forms the first line of defense, but after that, the best solution lies in maintaining that clear coat.

Professional auto detailers have a lot of tools at their disposal to do just this. Firstly, they know how to thoroughly clear away dirt so that attempts to repair clear coat don’t result in further scratching or nicks. Secondly, they often use microfiber rags that, in some cases, are enough to smooth out clear-coat damage on their own. They can also use a wet sanding procedure to remove a damaged clear coat before reapplying a new one.

How Often to Get a Clear-Coat Repair: Clear coats typically last up to three years, but the circumstances in LA might necessitate more frequent treatments.

Where to Go: Eco Auto Care (45 S. De Lacey Ave., Pasadena). These eco-friendly techs specialize in body and paint treatments.

The Problem: Salt

The Solution: A clay-bar treatment.

Iron and oxygen have always had a contentious relationship. Brought into close proximity, the two engage in a furious exchange of electrons that produces an unwelcome result: rust. Steel, like the kind cars are made of, is a little more durable than iron, but it still has a weakness to oxygen when exposed to saltwater.

Saltwater speeds up the process of electrolysis—the exchange of electrons—between steel and oxygen. This would seem to indicate that soaking your car in water to clean it is not the best way to prevent rust, but clay-bar treatments can help combat this problem. The clay bar’s flexible, soft surface picks up impurities left behind after a wash, leaving the surface of a car smooth and ready for a protective coat of wax that seals away the surface from rust-causing elements.

How Often to Get a Clay-Bar Treatment: Experts say at least twice a year, but three times couldn’t hurt.

Where to Go: Silverlake Auto Detail (4300 W. Sunset Blvd.). This highly rated, full-service shop does just about everything, including meticulous clay bar treatments to fend off rust.

The Problem: Smog

The Solution: A good, old-fashioned car wash.

The unfortunate effects of smog on human health are well-documented, especially in LA, but there’s some evidence to show that a buildup of smog can also cause discoloration on vehicles. Soot and smoke—both ingredients of smog—contain chemicals that can eat the finish off your car. Most technicians recommend doing a dry blow off of such materials before wetting a vehicle down and washing it thoroughly.

How Often to Get a Car Wash: In contaminant-rich environments, cars should be washed once a week.

Where to Go: Valet Detail Service (2239 Pontius Ave.). While the shop offers a lot of little perks to customers, what keeps people returning again and again are the detail-oriented hand washes.