Are K&N filters better than OEM?

This article discusses whether aftermarket filters, especially the ones by K&N, are better than the Original Equipment Manufacturer (OEM) filters.

Why are aftermarket filters on the rise?

Air quality has been degrading steadily over the past several years. This is more pronounced in urban areas, especially in places which are prone to traffic congestion. 

Amongst the many contributors to air pollution, traffic-related air pollution (TRAP) is one of the major contributors. 

In some of the major cities in the world, such as Beijing, Delhi, Los Angeles, and so on, TRAP causes poor air visibility and hazardous air conditions.

Therefore, many governmental organisations have mandated vehicular exhaust emissions in order to combat TRAP. 

The introduction of Euro emission standards, as well as greenhouse gases reduction programmes have helped to enforce these changes. Amongst these, aftermarket air filters for vehicles have also seen an increase in usage. 

With people being more environmentally conscious, as well as looking for ways to improve the efficiency of their vehicles, these filters have been finding a larger audience.

Furthermore, aftermarket air filters claim to offer many benefits over the OEM filters, such as low flow restriction, high dust-holding capacity, long life or service-free designs, high gravimetric and fractional efficiency, and much more.

OEM air filters

OEM stands for Original Equipment Manufacturer. OEM air filters are the engine air filters that are used in a stock version  of a vehicle. Usually, the price of these filters are included in the total cost of the vehicle. 

Stock filters frequently use a unique grade of paper for the filtering element. Please don’t be deceived; this isn’t the same type of paper that we use to write on. 

It’s a custom-made version that can catch dirt and other particles. Its main benefit is its inexpensive price and ease of replacement. 

The filter paper may appear to be flimsy, but it actually works fairly well if you replace it on a regular basis. The obvious disadvantage is that this slows down the air, which many believe prevents the engine from operating at maximum capacity.

Most stock or standard OEM air filters are constructed out of pleated paper or foam filter components, as well as fibrous materials with small enough holes to catch solid particle matter or dust in the air.

Air filters tend to become clogged with particulate matter as a result of high pollution levels, and it is advised that you clean or replace an air filter at every regular service of your automobile. 

The air filter has a direct impact on the volume of (clean) air delivered to the engine; if the pores are too small, it may provide greater filtering but inhibits air flow. 

Additionally, if the filter becomes clogged with particles over time, the engine receives less air, and thereby receives less oxygen.

K&N Filters

K&N’s classic high-flow air filters are made with 4-6 layers of quality cotton gauze pleated between coated wire screen mesh instead of a normal paper media. 

Cotton breathes more easily than paper, allowing for more airflow, less restriction, and improved engine performance.

A standard paper-based filter accumulates dust on its surface over time, but a K&N filter has many layers of fibre that retain dust particles. As a result, a K&N filter is said to hold more dirt per square inch than a paper filter.

K&N vs OEM Filters

There are various studies that have been designed in order to distinguish between the performance efficiency of a standard OEM paper filter and an aftermarket K&N filter, and how various engine parameters get affected.

We shall discuss some of the parameters mentioned below:

  • Fuel economy
  • Acceleration
  • Filtering efficiency

Fuel economy

Fuel economy refers to the distance a vehicle covers for every litre of fuel it consumes. It is measured as kilometres per litre (km l-1). The higher the value, the more efficient is the fuel utilisation of the vehicle.

Engine air filters play a major role in determining the fuel economy of the vehicle, as they regulate the air inflow, which in turn also regulates the oxygen supplied to the engine.

In the case of standard OEM filters, since they are made of paper, they offer a significant amount of resistance to the air inflow, and thereby also limit the oxygen inflow.

However, in the case of K&N filters, the design as well as the use of cotton provides an optimal air inflow to the engine. This in turn improves the combustion efficiency of the fuel, thereby improving the fuel economy.

Studies have shown that K&N filters provide a higher fuel efficiency than a standard OEM filter. Even as the filters clog, the efficiency decreases for both types of filters, but the K&N filter still outperforms the standard OEM filters.


Acceleration is the rate of change in the vehicle’s speed. A faster acceleration indicates a better fuel combustion efficiency, and thereby a better air inflow to the engine.

Studies have shown that acceleration time for K&N filters is less in comparison to that for the standard OEM filters. However, this difference is in the range of milliseconds.

As the filters start to clog, the time taken to accelerate to a certain speed increases. However, even then the K&N filter managed to outperform the standard OEM filter.

Filtering efficiency

Filtering efficiency refers to the efficiency with which an air filter gets rid of the particles present in the air flow. Within the air flow, dust particles also get trapped, which can find their way to the engine and therefore reduce the efficiency of its functioning.

In this case, filtering efficiency of standard OEM filters far outweighs that of the K&N filters. Given the way OEM filters are installed, as well as the pore spaces present in a K&N filter, the differences can be explained.

However, even this happens to be one of the reasons as to why one needs to replace their standard OEM filters in the vehicle on a regular basis. As the standard OEM filters start to clog, the air inflow reduces significantly, thereby reducing the oxygen supply. 

This in turn causes an inefficient combustion of fuel, which can give rise to serious pollutants such as carbon monoxide, nitrous oxides, volatile organic compounds (VOCs), and so on.

In the case of the K&N filter, since they aren’t as efficient as the standard OEM filters when it comes to filtering out dust particles, it can be attributed to the  increased pore size of the cotton gauze medium used in the filter. 

The actual filtering efficiency of the K&N filter will be higher in real life scenarios due to the increased surface area exposed to the air stream.

Replacement frequency and price

K&N filters are advertised as filters that, once installed, do not need to be replaced for a long period of time. This is true in some cases, as these filters have been shown to last for 10 to 15 years.

However, when it comes to the standard OEM filters, these filters need to be replaced, and the frequency of replacement depends upon the parameters such as the average daily distance the vehicle is used, the age of the vehicle, and so on.

When it comes to price, K&N filters are expensive when compared to the standard OEM filters, but only by a margin. This price gets outweighed when one considers the price for replacing the standard OEM filters regularly.

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K&N filters have an upperhand against OEM filters when it comes to performance of the engine, in terms of parameters such as fuel economy, acceleration, and the frequency of replacement.

However, in terms of filtering efficiency, K&N filters are less effective in filtering out particles such as dust, in comparison to the standard OEM filters.

This is because the OEM filters are made of a special grade of paper that cover the entire path of the engine airflow. K&N filters, on the other hand, are more porous, due to which more particles end up passing through.

Lastly, in terms of pricing, K&N filters are marginally more expensive than that for the standard OEM filters. However, K&N filters do not need to be replaced as frequently as the OEM filters.


What’s the difference between K&N filters and other filters that look similar?

Both airflow and filtration efficiency are critical to engine performance. Some companies design filters that provide high airflow by greatly reducing filtration efficiency, which can risk engine damage. 

K&N filters are designed to provide high airflow while also maintaining exceptional filtration. As the appearance of K&N filters has become popular, many companies have started offering products that mimic the appearance of K&N filters, but do not provide the same level of quality and protection.

Are K&N filters better for the environment?

Yes, K&N filters are better for the environment. K&N High-Flow Air Filters are designed to last for the life of your vehicle. If you assume an engine life of 175,000 miles-and replace your disposable air filter every 15,000 miles-only one K&N air filter will be used during the same period in which eleven disposable air filters are discarded.

This helps to reduce the waste generated in terms of air filters that one would need to discard on a frequent basis as in the case of the standard OEM filters, thereby reducing the toll on the environment.

How many times can I wash and reuse a K&N filter?

K&N High-Flow Air Filters can be cleaned and re-oiled using a K&N Recharger kit as often as is reasonably necessary. K&N drop-in replacement High-Flow Air Filters typically require servicing once every 50,000 miles under normal highway driving conditions, and the larger filters included with K&N intake systems can go up to 100,000 miles before needing to be cleaned (under normal highway driving conditions). Follow this link to view complete cleaning instructions.