Host: How often should I change my car's air filter?

David Rizzo: I would go by the manufacturer's recommendations, the car manufacturer. It will tell in your owner's manual. Odds are it's usually about once a year, once every 12000 miles. I certainly wouldn't push it any further than one year or 12000 miles. If you are in a dusty area like the desert where there is a lot of particulate matter in the air, sooner and certainly before any smart check change your air filter because you want to pass that test. If your air filter is clogged, this is what happens, the engine control unit adds more gas and naturally that's ruining you gas mileage because you are getting less air, it adds a little more gas to make up for.

So some big gains can be achieved by changing it on a regular basis, never let it go more than a year.