Replacing your car’s air filter is one of the easiest things you can do yourself and save money too. As a rule of thumb you should change the air filter every 10,000 to 12,000 miles, but check with your vehicle’s owners manual to be sure. If you live where the climate is dusty or there’s quite a bit of stop-and-go traffic in your daily travels, you’ll want to check your air filter more frequently since it can get clogged with dust, bugs and dirt quickly. Dirty air filters reduce gas mileage and produce poor engine performance.