How To Change Your Car's Filters

Any part of the car that takes in fluids or air from the environment should have a way of separating the good from the bad, of taking in only what benefits the mechanism and leaving the rest behind. This is why cars have air filters and fuel filters. True, they require regular looking after but this is one of the simplest and least expensive — and most important — maintenance procedures you can perform for your car. Changing your car's filters on a regular basis can have a significant impact on engine life and performance.

We'd like to walk you through a basic filter change. It doesn't take long, saves you money, and sends your car down the road refreshed and renewed. A clogged air or fuel filter can cause poor performance, poor fuel mileage and reduced engine life. This simple procedure guards against that.

How often should you do this? Check your owner's manual for the manufacturer's recommended intervals. If the manual's not available, a good rule of thumb is: air filter replacement every 12 months or 12,000 miles (whichever comes first); fuel filter replacement every 2 years or 24,000 miles (whichever comes first).

Changing the Air Filter

If nothing else, learn how to change your own air filter. It's quick and easy and saves you money.

How so? Chances are, the last time you went to the Quick Lube-n-Tune place the technician probably hit you up with, "Hey Bud, you need a new air filter." After which you nodded and watched as he added it to the invoice. How much? $17.99? $23.99? Heck, we've even seen $27.99.

The chief purpose of Edmunds.com is to empower the consumer. Don't let them stick it to you. Learn to say no — there's no law against it. Just say "Thanks, I'll look into it," and go home after the oil change and perform this procedure yourself — if, in fact, it really needs to be done.

First, park your car in the shade and pop the hood. Prop it up so it doesn't bang you in the head, then let the engine cool for a few minutes.

While it's cooling, go get your tools. You'll need very few for this procedure — grab a butter knife, two medium-sized screwdrivers, one standard and one Phillips, and head back to the car.

The air filter is typically enclosed in a black plastic casing near the center-top of the engine (sometimes, however, it will be off to the side). It should be the largest non-metal assembly you see, about the size of a breadbox. Find it? Good. Now, open it.

How? Well, most of them are held together by a couple of large metal clips on the side. Slide the butter knife or flat-headed screwdriver between the casing and the clip and then pry the clip away. Continue around the case's perimeter, loosening all the retaining clips which should allow you to open the case up. Occasionally you'll find an air filter housing that's held together with several long screws, in which case you'll have to unscrew them to get at the filter.

Should you own an older car (especially an American one) or truck, it might have a circular air filter (that's shaped like a big donut) located under a likewise circular metal housing sitting right on top of the engine. These are usually accessed via a simple, single wing nut atop the cleaner.

Anyway, crack it open and you'll find the air filter inside. It's usually white, bright yellow, orange or red, the better to see the collected dirt.

Pull out the filter — it's typically flat and/or elongated, and is made of a paper element with rubber edges to seal it against the casing.

Next, check it for cleanliness. Hold it up to the sunlight and (while keeping it at arm's length from your face) bend it back, so the paper ridges of the filter flutter like the pages of a book, and look inside the crevices. Do you see a lot of accumulated dirt and grime? Now look at it straight on. Is the orange or yellow paper mostly dirty in the center? If so, then you should replace it. It's not a big deal.

Close up the casing and put the old air filter in a plastic grocery bag. You're going to want to bring it with you to the auto parts store to compare old with new and make sure you get the right replacement. Toss it in the car and go clean up. By the way, it's okay to drive a car short distances without an air filter (something you can't do with a missing fuel filter).

Here's what you need to buy at the auto parts store:

• new air filter
• new fuel filter
• new gasket(s) for the fuel filter — they normally come with them, but ask to be sure

When you get back home install the new air filter. Seal it up and you're done.

Fuel Filter Replacement

This is a little tougher than replacing an air filter, since finding the thing can be half the battle. It's typically located near the top-center of the engine, close to the air filter, although sometimes, with more modern cars, it's actually built into the fuel tank and is a job best suited to your mechanic.

First, if you value your life, extinguish any smoking materials while doing this procedure.

Second, for better access, remove any oversized, plastic coverings from the top of the engine. They usually come off with a large, flat-head screwdriver.

Now search for the fuel line, which comes from the rear of the car. It's about the same diameter as a finger, and will be soft and pliant at this location, not a hard metal shaft. It will come into the fuel filter from the rear of the vehicle.

Find it? Okay, now grab a couple of # 2 pencils. You'll also need several different sized screwdrivers, both flat-head and Phillips, and a small ratchet set.

The fuel line will normally be secured to the fuel filter with a little clamp. Work it off with a screwdriver — usually a Phillips — and then jam the pointed end of a pencil into the free end to keep gasoline from spilling out. You may need a larger diameter object than a pencil, so you'll have to be resourceful here, since we don't know what you have lying around in your junk drawer at home.

After you've plugged the fuel line, you can remove the fuel filter. It's normally secured with a couple small bolts. Find the right-sized socket and remove the filter. It will also have a hose coming off the other end (this goes to the engine), so remove this one the same way you did the other one, and plug it with another pencil.

Compare the new filter with the old filter, and make sure you position it in the same way, so that the fuel is flowing in the right way. Sometimes there's an arrow on the filter showing you which direction the fuel flows.

Put the assembly together in the reverse order that you used to take it apart. Before you do, though, take a quick look at the new filter.

You'll note that there two metal (or plastic) shafts coming off the filter where the hoses attach. They have little nubs or ridges near the ends. Make sure to slide the rubberized lines onto the filter as far past the nubs as you can get them.

Also, pay special attention to the clamps on either end of the filter. Position them between the nubs and the body of the filter. Then get them snugged down good and tight (but not so tight as to strip the screw), to prevent leakage.

One last thing. If the hoses are getting brittle and frayed, make a mental note to buy some new hoses next time you change your filter. If they're really bad, replace them now.

After you have everything reassembled and secure, run the engine for a few minutes. Inspect the hoses and connections to make sure no fuel is leaking.

That's it.

Remember, next to changing your oil and oil filter, replacing your air and fuel filters on a regular basis is the single most important act of maintenance you can perform for your engine. Do it and your engine will thank you by giving you many thousands of trouble-free miles.