How do I choose an air filter for my car?

How To

When to change the air filter, how to choose, what to focus on, how not to buy a fake, tips on brands – the answers to your questions you will find in this article.

Buyer’s Guide to Selecting an Air Filter

The air filter is the mechanism that allows your car to “breathe” as the air coming into the engine passes through it. The longevity and performance of your engine depend on the quality of the air filter, and the engine is clearly the most important element of your car.

Purpose and principles of operation of the air filter

A perfectly running engine consumes approximately fifteen kilograms of air per liter of fuel. At the same time, the air entering the combustion chamber must meet stringent standards for:

  • Temperature optimality.
  • Oxygen saturation
  • Have an average density
  • The total absence of impurities affecting the operation of the engine

Getting a small amount of dust, scale, rust or other debris will easily disable the engine. That is why it is very important for a chauffeur to choose an air filter to make the car feel confident on the road and work with any load. The most common type of dirt is road dust and sand, which is picked up by the vehicles ahead. Small imperceptible to the eye grains of sand, getting inside the combustion chamber, become the reason for the quick breakdown of metal surfaces. Another thing that strongly affects metal is high humidity. Aggressive vapors cause corrosion and eat away at the cylinder mirror.

The main purpose of any air filter is quality engine protection from ingress of dust, furnace, debris, and excessive moisture. A quality filter extends engine life by 18% in city conditions and by up to 150% in off-road conditions.

The filter consists of a solid metal housing with a special synthetic fabric element. Passing through the multilayered surface of the flow material, the air is cleaned of any impurities. The flow then enters the flowmeter and then into the combustion chamber. Filters are always installed in such a place that the old filter insert can be replaced easily, without resorting to the services of a workshop. A little about the types, types, and features of the design.

Today, every car that comes off the assembly line is guaranteed to have a paper air filter with different parameters. Carbon and oil filters have become a thing of the past, as paper filters are much more reliable and compact. In turn, manufacturers do not stand still but try to create new materials with which you can improve filtration without a significant increase in geometric dimensions. For example, there are more than 300 kinds of paper that are used in filters. Filters with an additional layer of porous synthetic material are increasingly appearing. Synthetics still outperform paper in both filtration quality and durability. However, the natural material will be the basis of many automotive consumables for a long time to come.

Filter paper is impregnated with various compositions. Many include resins. Such impregnation is needed to ensure that the material does not leak water and in contact with it did not lose its properties. Thanks to these compositions, the filter performs its work in conditions of extremely high humidity, is able to endure the impact of microscopic particles of gasoline, oil, fuel oil, and other aggressive chemicals, with which the car interacts.

And it also uses depth filtration technology to extend service life. In essence, a multi-layer structure, in which each layer is riddled with a different number of pores. Such a filter is already more complex than a conventional single-layer filter. It selectively filters out the larger particles on the upper layers and the smaller ones on those in the middle of the filter element. In this case, the air passes through several layers of material without encountering much resistance.

Filters can be shaped as follows:

– Ring-shaped (circular) – such filters are rarely seen on modern cars, as they were installed on models that were equipped with a carburetor system. Since when the car is moving air movement causes quite a lot of pressure, such filters did not do without a reinforcer in the form of an aluminum mesh frame. The product of this form can not boast about the performance, takes quite a lot of space, but the useful area for direct filtration is very small;

– Panel filters (with and without frames) – today such filters can be found in most cars. They are installed in cars equipped with an injector or diesel engine. In such filters to improve the strength of the filter element is equipped with metal or plastic walls. They reduce the deformation of the filter itself, keeping its quality and reducing the useless consumption of its resource. These filters are very versatile as they contain everything necessary for quality and reliable air cleaning in any conditions;

– Cylindrical filters are an improved version of circular filters, getting rid of their main disadvantage. They are used in special vehicles, mainly diesel engines. Also, they can be found in an ordinary city car, but only with a similar engine.

How many degrees of filtration there are and what is the difference between them:

  • Degree 1 – in this case, the filter holds only a special paper, which is folded as tightly as possible. There is nothing complicated here because all the work of air filtration is undertaken by a single element;
  • Degree 2 – unlike the previous type of filtration, a pre-cleaner is used here. This is a special synthetic material, which does not allow larger particles to penetrate the filter element. It proves to be very good in dry and unfavorable environment, e.g. when driving frequently and for a long time on dusty terrain or country roads
  • Degree 3 – Here, the air is cleaned of particulate matter before it enters the filter. The fact is that the particles coming with the air under the influence of cyclone rotation are slowed down and fall into a special container. A special impeller is responsible for creating the cyclone.

Read more about the requirements for air filters

The filter’s job is to free the air as much as possible from coarse and fine particles of dirt, dust, lint, insects, etc. Almost all foreign impurities, which can be harmful to the engine, have to be filtered out. Naturally, complete filtration is very difficult to achieve. Initially, engineers simply tried to make the filter element as dense as possible, so that it would trap all the solid impurities.

The peculiarity of automobile filters is that they should not create much resistance to the flow of matter passing through them. In air filters, the idea of minimizing resistance has not yet been fully implemented. Engineers are pushing back on the opposite – which you absolutely must not do. And then it becomes clear that increasing the density of the filter material has a certain limit. In this case, even the high quality of the product does not help to combat the disadvantage. A dense filter that captures all impurities quickly clogs and creates an obstruction to the air flow.

Today, the solution to almost all air filter problems is perfect proportions:

  • The auto is designed to have an airflow resistance of approximately 0.5%;
  • The filter prevents about 98.5% of dust, dirt, and other contaminants from getting into the ICE;
  • The maximum air filter resistance is 50 kPa. At this resistance, the filter itself becomes completely unusable, as it will be saturated with soot and dirt. There will be no airflow. The normal resistance should not exceed 2 kPa.

Naturally, in addition to the various technical parameters, there are also the wishes of consumers. Fail-safe operation throughout the period of use, certain dimensions, good product assembly. All these requirements must be taken into account by a serious manufacturer. Looking ahead to say that the difference in the price of consumables between large Japanese or German firms and little-known Chinese and Polish is enormous. One branded filter can cost as much as a few “no-name” analogs.

The Proper Use of the Air Filter

When the old air filter breaks down, the car owner needs to do three things: buy a quality replacement, install it correctly and watch how dirty it is in the future. You can do a visual inspection, or you can follow the readings of the contamination sensors. As you see, everything is simple enough.

It is necessary to change the filter, first of all, proceeding from the regulations, which are clearly described in the service book. If to take into account the fact, that different cars are equipped with filters with different characteristics, it will be more correct to act according to the manual, instead of recommendations of familiar motorists.

The filter is not always changed as specified, especially if you frequently drive your vehicle in harsh conditions. If you drive regularly on dusty country roads, in sandy or smoky areas, change the filter twice as often as specified.

Check the air filter more often if:

  • You drive frequently in areas of high dustiness;
  • It is late spring and summer when there is a lot of pollen, small insects, etc. suspended in the air;
  • You often drive on country roads;
  • There is a constant accumulation of smog in your city.

Note also that the location of the air intake greatly affects the “life” of the filter. Naturally, the worst option is next to the exhaust pipe. After all, at this location, the system will take the air with increased temperature, enriched with soot and gasoline or diesel vapors.

Pay attention to the area of the filter element. Here’s an example: if our conditional filter is small and has one degree of filtration, it is risky to put a turbo on the car without picking up a new filter. The turbocharged engines take in more air than normal engines without modifications. The volume of air passing through the filter has increased – so has the rate at which it clogs. In this case, it is better to put a new consumable with a larger filter element and with multi-stage cleaning.

Some motorists think that only oil filters need to be replaced in time. In fact, there are a lot of advantages to quality air filtration.


That’s why it pays to change your air filter on time:

  • You will forget for a while about the unclean air, which in the long run can provoke a failure of the engine and many related units;
  • Minimizes fuel consumption;
  • Minimize wear and tear on engine parts involved in friction;
  • The fouling of fuel injectors will be reduced.

Specialists recommend replacing at the same time as every other change of old engine oil. If a visual inspection reveals the bad condition of the consumable, it should be changed either as soon as possible, or at the same time as the next oil change.

It is possible to change it yourself. You do not need special tools and a good knowledge of technique. However, we advise you to change the air filter during your visit to the service station. If you have decided to change it yourself, you can not forget about two things. First, remove the old filter with great care. The fact is that the dust can get into the manifold, where it will continue its way to the engine directly. Secondly, check that the housing cover is tightly closed after work.

Important things to watch out for

You have real cause for concern when you find the following:

  • The air filter is critically contaminated;
  • The filter element or housing shows signs of mechanical damage;
  • The consumable has not been installed correctly.

In fact, there can be plenty of problems with the air filter. But there is one thing. If it was properly selected, properly installed, and in general meets all quality standards, over time it will simply get dirty. So if the element that was selected as a replacement for the original fails earlier than it is supposed to, you should first pay attention to the manufacturer of this filter and the matching parameters of OEM and purchased parts. However, it is impossible not to note the low, but all nonzero probability to buy a defect from a serious factory. So every time you buy an air filter you should carefully inspect it.

The first sign of a dirty filter is the inflow of insufficient amount of air for the engine to function properly. With this, the driver will notice a drop in power, a deterioration in the quality of the exhaust, and an increase in fuel consumption. Over time, these problems don’t go anywhere, as they sometimes do with a faulty thermostat, for example. A clogged filter will only continue to collect dirt. The final stage of the disease: the car starts moving with great difficulty and at some point stops driving at all.

The antipode of a clogged filter is its mechanical deformation. As soon as there are breaks and tears on the element, the quality of filtration is reduced to zero. All the dust, soot, dirt, combustion products of transport, and many more things will get inside the car. At that, contamination is as if selective: first, the injectors will suffer, then the cylinders with pistons will quickly wear out with a little lag.

On the prospect of cleaning an old filter

Many manufacturers today are in the process of developing new materials or applying the latest technology to create better “lighter” cars. But there are still those who are smarter and more economical than everyone else. In their opinion, the purchase of a new air filter is not justified, because it is possible to renew the old one and continue to operate the car as usual. So many interesting ways of “reanimation” of car consumables were invented (vacuuming, knocking out, washing with detergent, soaking with oil, etc.).

Is any of the above worth trying? No, you will only partially restore the product to its marketable appearance. The peculiarity of the filtering materials used is that their level of contamination can, in principle, only go upwards. Knocking them out and washing them does not help – the smallest dust and dirt, which is a great danger for the engine, stays inside the filter. And if you do clean it and put the unworn consumable back in, you’ll get nothing more than an instant increase in fuel consumption. In addition, large particles trapped by the top layer can still separate from the filter and get into the air duct.

The strangest idea seems to be to wash the filter paper with oil. The fact is that this is the fastest and most reliable way to clog the micropores, thereby impairing the filter’s ability to pass air.

Hence the conclusion: a consumable is consumable, so when its service life is over, you just throw it away and pick up a replacement. It concerns not only air filter. No way of cleaning has ever managed to give any appreciable result.

What does the price of the air filter depend on?

The final cost of the filter affects the following: the area, material, manufacturing technology used, optional impregnation, the presence of the impeller, the frame. For example, you can buy an auto filter for an old car for mere pennies, as they are made of inexpensive paper and do not guarantee high purity of air.

In the past, there were no serious requirements for many car filters. They put more serious filters on modern cars. They can already selectively trap pollutants of certain sizes at different levels. The best consumables today are wetted with a special mineral oil. Such a filter works much better than a conventional one, even though they may both have the same geometry and layout.

Here’s one peculiarity: you can see small oil droplets on the surface of the oil-soaked element. They, firstly, prove the fact that a fairly sophisticated and advanced technology is used, and secondly, indicate to buyers the branded part. It has not yet been possible to counterfeit impregnated filters. You can see the difference between the counterfeit and the original with the naked eye.

Choosing a brand of air filter

If you take into account the fact that the manufacturer is guided by the parameters of specific models of vehicles and on incoming orders, it is best to choose the filter with the VIN code. In this case, you surely will not encounter the fact that the part is incompatible with your vehicle.

Another option: search by make, model, and engine parameters.

Incompatibility is possible, but you will greatly reduce the likelihood of a bad outcome if you buy from an official store.

And lastly, try to find out the code of the stock part. With that, you’ll be able to find the original. If you start looking for the air filter in the electronic catalog, knowing just one code, you will be able to find the nearest analogues. Unfortunately, there aren’t many companies on the market today that offer quality consumables to motorists.

Here are some of the best:

  • Fram (US)
  • K&N (US)
  • ACDelco (US)
  • Delphi (US)
  • Bosch (Germany)
  • Mann (Germany)
  • Mahle (Germany)
  • Denso (Japan)
  • UFI (Italy)
  • Blue Print (England)

Budget options:

  • WIX (Poland)
  • Profit (Poland)

All these manufacturers are not the first to occupy a niche in the market and have huge experience. German and Japanese filters, though expensive, in quality are almost as good as the originals.


The air filter can be deservedly called the “lungs” of the car. And what your car breathes is of great importance. Reliability and uptime of the engine and all mechanisms, which are in it, depend on many factors. The cleanliness of the incoming air for the fuel mixture is one of them.

You don’t need to be an expert in air filter maintenance. If you limit yourself to regular visits to the service station and keep an eye on the cleanliness of the filter element yourself, you won’t have any problems.

When the time comes to change the consumable, take the choice of replacement very seriously.

Firstly, nowadays it makes sense to buy expensive filter models because they work better with modern cars, whose systems react to the slightest pollution.
Secondly, a good branded part is easy to distinguish from a fake. And affordable in price terms as well – you only need to study the marking of the product, its packaging, the state of the filter material and find out more about the manufacturer. If you are offered an inexpensive product, whose manufacturer you have never heard of, please refrain from buying. We advise you to avoid markets. It is better to look for parts in specialized stores and online.

David West
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