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As we learned from Lloyd yesterday, keeping your car tuned up is a great way to save some cash and maintenance over the long haul. If living car-free isn't an option, then keeping your ride running properly is an essential way to not only get better gas mileage and keep maintenance costs down, but to insure that you get the most out of your car, and that you have a mutually-beneficial relationship for years to come. In addition to these tips, we'd like to add one more: replace your car's air filter with one that'll last a lifetime.

Most disposable air filters are rated to last 15,000 miles or so; for many of us, that's once a year or every 18 months. So, while you don't do it as often as, say, filling up with gas, keeping up with it is absolutely important; the U.S. Environmental Protection Agency estimates that a clean air filter can boost your gas mileage by 10 percent over a dirty one, which, at today's gas prices, adds up to about 31 cents per gallon. When it comes time to replace your current air filter, going with a "lifetime" filter will save you the trouble (and the cost) of dropping a new one in there every year or so. And, luckily, it turns out that changing and maintaining your air filter is easy.First off, your air filter is usually located either in the top-center or on either side of the engine -- it's the orange-bordered guy on the left in the picture above-and its often encased in plastic housing, to keep it from getting damaged. Once you've found it, and determined it's time for a new one, head on over to your favorite auto parts store, or manufacturers website where you can search for your vehicle make and model, to pick one up.

A lifetime filter will likely be twice as expensive as the disposable kind, but will pay for itself many times over (especially if your car is new, or you plan to crank out another 100,000 miles before it goes to the great parking lot in the sky).

Once you have the new filter in hand, changing it out is one of the easier things to do on most cars. Locate the housing-older cars often have a round, donut-like filter right in the middle, while newer cars tend to be off to the side (and in a square housing). Most are either held together with two metal brackets or long screws; use a flathead screwdriver (or your fingers, if you can) for the brackets and whichever screwdriver matches the screws holding it in place. Once you have the housing open, it's a simple replacement; lift the old, dirty filter out, and replace it with your shiny new one. Replace the housing and you're done!

For reference, we recommend that you peruse these manufacturer instructions (PDF) and keep them handy, in case you get stuck. For the more visual learners, the gearheads at Edmunds also have a handy video to show you how. The lifetime filters need only be inspected every year or so; when they appear dirty, follow the manufacturers' instructions for cleaning and care, and revel in the fact that you'll never buy another air filter for your car again.

Difficulty level: Easy