Cars breathe the same air we do, but far more of it. The typical car engine will breathe 10,000 gallons of air for every gallon of gasoline burned. This air must be passed through a filter to avoid introducing contaminants into the fragile inner workings of the engine. With use, a car will need a replacement air filter to maintain fuel efficiency and peak performance.

Replacing your customer’s car’s air filter isn’t especially complicated, but it must be done regularly to keep it running in tip-top shape. The car air filter replacement cost will be far lower than the cost of decreased fuel economy, or the various maintenance issues that can result from driving with a dirty filter. These potential automotive repair costs can get expensive, so customers should know these facts and how your auto and car care services can help create long-term cost savings.

The purpose of the air filter

The air on the streets and highway can be full of dust and debris. Engine air filters trap harmful dust particles and other contaminants before they can enter the intake tract. The filter material allows the free flow of the air the engine needs to breathe for efficient combustion, while keeping out larger particulates. This material contains many small holes, also sometimes called “pores.”

Modern air filter elements are designed to flow air with maximum efficiency. In fact, most modern engines produce less power with the filter removed for testing than they do with it in place. Filter design has come a long way over the last few decades.

Filter materials

Most car air filters are made of pleated paper. The pleats increase the surface area of the filter, increasing its breathability and lifespan. Some cars use semi-permanent foam-based filters, some of which require regular cleaning and re-oiling. Foam filters are typically used in high-performance or severe-use applications, and are provided as aftermarket accessories by companies like K&N. For the purposes of this article, we’ll focus on paper-element factory-style filters.

How to tell if your customer’s car needs a new filter

While you should inform customers to check the car owner’s manual for the factory-recommended interval guidelines, it’s typical to replace air filter elements every 15,000 miles or so, or as required by the conditions under which the vehicle is used. A 4×4 truck used to access remote campgrounds along dirt roads while traveling in a convoy will need more frequent filter replacement than a minivan used to take the kids to school on paved city streets. Let your customers know that in many cases, the best approach is to periodically check the filter for cleanliness and condition in between recommended replacement intervals.

What happens when the air filter gets dirty

When your customers come in for servicing, inform them that the first symptom of a dirty air filter in deep need of replacement will likely either be decreased fuel mileage or performance — or possibly both. A car that can’t breathe adequately due to a dirty, clogged filter will accelerate more slowly, causing the driver to use more gas when leaving from stops or passing.

A longer-term consequence of a clogged filter is increased deposits on the engine valves, spark plugs, or fuel injectors. Not only can these deposits be expensive for customers to have corrected, but they can also result in failed emissions tests and difficult starting.

Let customers know that regular car air filter replacements cost less than correcting the problems that can result, and fuel savings alone can make it worthwhile.

How to change a car’s air filter

It’s important to have the customer leave you the proper owner’s manual or have a trusted online resource available before starting this task. Sometimes, the proper method of removing the air cleaner assembly cover over the air filter isn’t obvious. It’s common to accidentally break connectors or fasteners during this step, so some reasonable caution is advisable.

Open the car’s hood

Locate the air cleaner assembly. This can be somewhat difficult if you haven’t worked with a certain make or model before. Refer to the manual or online resource.

Open the air cleaner, following the directions in the owner’s manual or other resource.

Check the filter

Once you remove the filter, check to see if it’s dirty. One old mechanic’s trick is to hold the filter up to the sun or just a bright light. The filter material should glow with the light behind it, and some specks of bright illumination should show through here and there. If no light is visible, it’s high time for a replacement.

Replace the old filter

If the old filter is indeed dirty, replace it with a new filter, being careful to ensure that it is seated correctly.

Reseal the air cleaner assembly, carefully replacing the fasteners. Be sure not to disturb any electrical or vacuum hose connections.

Close the hood

Start the engine, take a test drive, and enjoy the increased performance and efficiency.

If these steps make it seem simple, that’s because it is.

What to do with the old filter

If your community has a recycling program, it’s best to dispose of the filter with other waste paper if possible. This is appropriate if the air filter hasn’t been contaminated with oil or other chemicals. In the U.S., tens of millions of air filter elements are disposed of each year. Recycling them keeps them from going directly into landfills, where they will take up valuable space while biodegrading very slowly.

Check with your local recycling program to see if air filter elements are appropriate for the paper recycling bin.


Mike Fulstrom is an automotive enthusiast and blogger. He enjoys helping people learn how to take care of the little automotive issues and saving them money.