Friday Fuel Economy: Change Your Air Filter

Reader Contribution by Staff

Here’s another easy way to boost your gas mileage, and help maintain your car’s engine to boot: change the air filter. Swapping a dusty, dirty air filter for a new one can improve fuel economy by up to 10 percent and result in gas savings of about 32 cents a gallon.

If you have your oil changed at Jiffy Lube or a similar quick lube joint, you know that they hit you up to change your air filter practically every time. Don’t fall for it. And even if you do need a new air filter, buy one elsewhere and change it yourself — you’ll pay about $5 to $10 for a new filter from an auto parts store vs. anywhere from $15 to $30 from the lube joint.

How often you should replace the air filter depends on where you live and drive. City slickers should probably do so once or twice a year, or after 12,000 to 15,000 miles. Rural residents or those who regularly drive on non-paved roads might need to change their filters more often.

For almost all cars, changing your air filter is easy — if you can turn a screwdriver, you can do it. Start to finish, you can change the filter in less time that it takes to wash your car. You probably won’t need any more tools than a screwdriver; for many cars you won’t even need that.

  • First, decide if you even need a new filter. Park your car, apply the parking brake and pop the hood. Now locate the filter box — it’s usually black plastic and is probably located on top of the engine or off to one side. The box will be held shut by screws or some sort of clasps. Open it up and examine the filter. Be sure to note how the filter fits in the box so you can put it back right or install the new one correctly.
  • Most filters are some shade or red, orange or pink, and are made of stiff paper that look stacked like a hardback book with thick paper or folded tight like a nearly closed accordion.
  • The filter might be really nasty and clogged and you’ll know right away you could use a new one. But even if it’s moderately dirty, you might not need to replace it. Gently knock it around to see how much dust and dirt you can shake out. Stretch and thump the paper folds to see what more you can get out and how much is trapped between the folds. You could even run a shop vac attachment across it (gently, of course).
  • If after all that it remains really sooty, you’re due for a new one. Be sure to clean out or vacuum out any leaves, dead bug remains, etc., out of the filter box.
  • Next, put the filter back in (for now) or leave it out — it’s fine to drive short distances without one plugged in, but do close the box. While your local auto parts store should be able to look up the right size filter for your car, it’s not a bad idea to take your current one in with you to be sure you get a perfect match. 
  • Last, drop in the new filter and close its case. Your car will now breathe easier and deliver better gas mileage.

Click here and here to see how-to videos of this process.

John Rockhold is a green car enthusiast and Contributing Editor for MOTHER EARTH NEWS. Find him on .