What is a car engine air filter and when to change it

The air filter is an important component of a car because through it the engine “breathes”. Every car has an air filter, from the earliest models, and all filters have the same purpose: cleaning the air before it reaches the intake manifold and the engine.

But not all air filters are the same, not all look the same, and not all behave the same, the air filter is one of the first components under the hood. Here’s everything you want to know about car air filters.

No internal combustion engine can run without air. An engine without an air filter can work, but only for a very short period.

What does an engine air filter do?

Usually, air filters for cars are made of a material such as cardboard, fiber, or even textile or sponge. Regardless of the material from which it is made, the purpose of a filter is to prevent particles larger than several microns from entering the air in the engine.

Usually, the air filters are from the classic material that looks like cardboard but is porous to allow air to pass through it. Also, the material is mounted in the frame or zigzag support to create a larger surface for absorption.

The air filters are positioned as the first element of an intake route, before the flow meter, the throttle, and the intake manifold. Usually, the filter in a standard car is mounted in its own plastic housing, which has a specially positioned mouth so that it draws as much air from the outside.

Air filters are usually rectangular, with a rubber frame for tightness, being mounted horizontally. But there are other forms of filters, depending on the car.

Are air filters necessary or optional?

Technically speaking, an engine would prefer not to draw air through a filter. And that’s because it’s like drawing air into your chest with a pillow on your face, which will be harder for you.

An engine would be “relieved” if it didn’t have the air filter barrier when it breathes, but the risks are quite high. Any dust particles or other debris can enter the engine, use the pistons prematurely, clog the catalyst, etc.

That is, the lack of an air filter that costs very little can lead to huge expenses.

There are isolated cases in which drivers choose to go without the air filter, either at racing or to impress the world with the sound of the engine. It’s more thrilling, but it’s not healthy at all.

Therefore, every car must have a filter, be it stock or sports. It is important to check and replace the air filter quite often. It is also good to know where this air filter is located in your car.

car engine clean air filter vs dirty filter

Clean engine air filter and dirty air filter

How long does a car engine air filter last?

It depends a lot on the driving conditions. If you make many stops and starts, especially in crowded places, or if you spend time on off-road roads you will probably need to replace the air filter much more often than someone who drives less and usually on long journeys.

The air filter should be changed somewhere between 4500 and 75000 miles and it would be ideal to change your engine oil at the same time. Or at least, you should do an oil check. In short, it doesn’t cost you anything to take a look, you’ll avoid costly repairs later.

Regardless of these instructions, given that air filters may be used differently, you should know the symptoms that indicate that the air filter needs to be changed

  • a significant increase in fuel consumption;
  • ignition problems, a slow start, or failure to start; engine failures;
  • slow idling;
  • check engine light is on. In general, if you feel the performance of the car decreases

If you experience any of these symptoms, you will need to replace your emergency air filter.

Therefore, a dirty air filter can lead to more problems than any driver would want. And it is strange because the air filter is perhaps the simplest part of a car, the cheapest and the easiest to replace even by an amateur.

Engine sport air filters – myth or reality?

The market for sports air filters is full, more colorful, brighter, and sweeter with power ratings. Some even write that they give 10-20 extra horsepower! But this is only for believers who have the impression that if they change their filter, the car gains hundreds of extra horsepower.

Different studies and tests with normal air filters and sport air filters have had only one result: conical air filters, or sport, rarely give 1-2 horsepower more than normal, never more.

And this is only in the case of quality filters. A common sports air filter will likely offer even more power because it is of a worse material, which allows many particles to pass, but also more air. That’s not good for the engine.

Consolidated filters are made of high-quality materials, at least as dense as the factory ones, meaning they don’t let even the smallest strands of dust pass, but they offer a larger surface area of absorption.

For example, a conical filter will draw air through it, but also through the entire outside, instead of a rectangular one pulling only through one side.

Therefore, sport filters do not have a material that allows more air to enter the engine but have a larger surface through which the air can be absorbed by the engine. And as a conclusion to the eternal question:

Do air filters offer more power? There is only one answer: by themselves, NO!

That is, if you want to feel some increase in power for your engine, apart from the air filter, you have to replace the intake route as well as the exhaust. So the engine will inhale better, but it will exhale easier.

Which air filter to choose?

Premium air filters

They provide optimum airflow to the engine for the performance for which it was created. As I mentioned earlier, it is a false thing that a sports air filter increases engine performance.

A sports air filter provides the engine with the air it needs to develop the factory-designed power. The number of horsepower will not increase. 

Premium filters have a longer service life and allow a higher airflow to enter the engine than normal ones. But keep in mind, that the more residues and dust the engine gets, the lower the engine performance will be.

What does a good engine air filter mean?

The surface of the air filter is full of pores with microscopic openings, so small that it is measured in microns. The thickness, density, and size of the openings in microns determine the quality of the air filter.

The smaller the openings, the better the filter. Many times, when we look closely at the air filters, they all look the same. The poor quality filters are made of thin paper, a little thick, and with quite large openings, leaving a lot of dust to pass through them.

A better quality filter has smaller openings than hair, and less than 50 microns to prevent even the smallest dust particles from getting into the engine. They also have more skin to prevent and capture larger debris.

What air filter should I buy?

As for money, a cheap filter costs 10 $ and a performance filter from 65 $, so the difference is quite large. But let’s think about how much it would cost to repair the car’s engine. When choosing the air filter for your car, keep these factors in mind:

  • have a cleaning capacity of at least 98%;
  • the holes should be as small as 50 microns;
  • have a longer life span;
  • be the same as the original filter or even more efficient.

How do I replace the air filter in the car?

Usually, the air filter is encased in black housing, which has a lid fastened with clips or a few screws. Any air filter is positioned so that it can be easily replaced by anyone, so we do not need a visit to service for this operation.

The lid that hides the air filter should be raised slightly, weakening a few clips, and the old filter will come out easily. We insert the new filter instead of the old one, taking care to put it with the indicated part down. We put the clips in place and our engine is now enjoying the fresh air.


The air filter of your car is a very important element, which lets your engine draw fresh air, thus providing the safety and reliability you need. It is a cheap piece that needs to be changed in time, before other problems arise, so essential in the smooth running of the engine.

And sports filters, on their own, do not do much. But in combination with other changes to the inlet and outlet, they will give a better performance than the stock.

Also, a sports filter that is not protected by the original housing will have a more aggressive sound and will look cooler, giving the impression to uninformed people that, under the hood is hidden serious power.

However, make sure you change the air filter in your car when you need to, and you will have no problems!

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