What to Know About Your Car's Air Filters

Neglecting proper maintenance can hinder your vehicle's performance and hurt you in the pocketbook over time. Air filters are crucial to your vehicle’s performance and your own comfort. That’s why it is important to know how often to change the air filter in car. Understanding this, along with other aspects of your vehicle's filter, will help to keep it running smoothly for years to come.

The first thing to understand is that cars have two different air filters: a cabin air filter and an engine air filter. They filter air for the interior cabin and the engine respectively. This article will mostly focus on engine air filters.

1. What the Engine Air Filter Does

The internal combustion engine needs more than gasoline to start and take you where you need to go. It needs a continuous supply of air to mix with the gasoline to work properly. The challenge is that harmful contaminants in the air and materials such as dirt, grease, and other debris could damage your engine. Over time, these factors could eventually make your car unfit for the road or unable to run at all.

When you consider what a car’s air filter does, you’ll understand the vital part it plays. The filter keeps these contaminants out of the intake manifold and cylinders, letting your engine run one clean air. As air moves through your car’s air intake, contaminants are caught in the filter media, which is porous enough to allow air through, but not the contaminants. This can prevent severe engine damage, so you should never drive without an engine air filter. If you replace the filter regularly, your car is less likely to experience other problems.

2. Replace it on Schedule

There’s a lot to remember when it comes to car maintenance. Many parts of your vehicle will require attention and will need to be replaced or repaired at some point. As the air filter does its job, it will become dirty and filled with debris that it separates from the air that goes through the intake. This will restrict air flow and hurt the vehicle’s performance. Before you get to this point, make sure you replace the filter. You can do this yourself if you have the time and skills. Or, you can find a competent mechanic to do it for you.

When you should replace your engine air filter depends on what you drive. It’s said that you should replace yours every 10,000 to 15,000 miles, but your owner’s manual will have the precise service interval. Another good practice is once every 3 oil changes. There are also some lifetime air filters, which you regularly clean instead of replacing. Be aware that you’ll more likely have a dirty air filter car if you often drive in heavy traffic, or live in a dusty, rural climate where you travel dirt or gravel roads. In this case, it’s a good idea to replace the filter every 5,000 to 6,000 miles. Many car owners replace the filter at the same time and place as an oil change.

3. Replace it When Gas Mileage Starts To Suffer

It is wise to keep a close eye on the efficiency of your vehicle. A car with good gas mileage will save you money in the long run. When gas prices are high, you may pay even more attention to your vehicle’s gas mileage, particularly if you drive it a lot. Here’s how the filter impacts the gas mileage:

  • When the filter is dirty, airflow is restricted and less oxygen gets to the engine.
  • The engine makes up for this deficiency by using up more fuel.
  • This way, the car still gets the power it needs but requires you to fill up more frequently.

4. Replace it if it Looks Filthy

Sometimes, knowing when to change the air filter is a simple matter of taking it out and examining it. A new air filter is generally white and clean. Gradually, as dirt and dust build up, it will turn gray or brown. This is normal and should not cause much concern. The darker it gets, the more likely you should replace it. By the time it’s black and caked with debris and dirt, you should make the switch. If you’re not sure, check your owner’s manual for the proper service interval or talk to a mechanic. You’re better off replacing it sooner than necessary than you are driving around with a clogged filter.

5. What is the Cabin Air Filter?

The cabin air filter keeps the air inside the car clean and safe. It works similarly to an engine air filter in that the filter’s media lets air pass through and stops dust, spores, and other unwanted materials. In this case, the car’s heating and A/C system draws fresh air from outside the vehicle, in through the cabin air filter. You may wonder how often to change cabin air filter, and the good news is that you won’t have to replace this as often as the engine air filter. Usually, changing it every 20,000 miles or annually should keep enough to keep air flowing nicely. To be sure, consult your vehicle’s owner’s manual.

A common sign of a bad cabin air filter is a moldy or musty smell when you turn on your AC or heat. On most vehicles it can easily be removed from behind the glove box, and it should be pretty evident if the filter is dirty or not once you take a look. Replacing the cabin air filter is a fairly straightforward job that most people can do at home. Make sure to replace dirty filters, as they can otherwise restrict air flow, causing greater strain on the air conditioning system.

If it’s time to replace either of your car’s air filters, stop by your local AutoZone to get the parts you need. Find the right fit by entering your vehicle’s information on, or by talking to an associate at your local AutoZone.

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Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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