K&N Frequently Asked Questions (FAQ)

Air Filter Tech and Performance

  1. How will a K&N filter affect my vehicle's fuel economy?
  2. What increase in horsepower should I expect from a K&N replacement filter?
  3. What increase in horsepower should I expect from a K&N air intake system?
  4. Can a K&N filter give my engine too much air flow?
  5. What is the micron rating and efficiency of a K&N air filter?
  6. What are the air filtration requirements for my vehicle?
  7. Some air filter companies tout their high filtration levels in the 99th percentile. Doesn't higher filtration mean a better air filter?
  8. More airflow means you are letting more dirt through, right?

Air Filter Cleaning and Oiling

  1. How often do I need to clean my K&N air filter?
  2. How much oil should I use to re-oil my filter after it is cleaned?
  3. Can I use anything other than K&N cleaner and oil?
  4. Can I use compressed air to dry the filter faster?
  5. Can I use a brush to help dislodge dirt on my filter before cleaning?
  6. Do K&N air filters come pre-oiled or must they be oiled before using?

Warranty

  1. Will using a K&N replacement air filter or intake system void my factory warranty?

Emissions Legal

  1. Are K&N filters emissions legal?
  2. Are K&N performance air intake systems or RK-series custom air cleaner assemblies emissions legal in the US?

General Info

  1. Can a K&N air filter be made at the factory for any application?
  2. My filter came with a tube of sealing grease. How important is it?
  3. Will a K&N filter cause my vehicle's mass air sensor to fail?
  4. Can a K&N product cause my Check Engine Light or Service Light to come on?

Air Filter Tech and Performance

1. How will a K&N filter affect my vehicle's fuel economy?

K&N does not make any claims or advertisements regarding fuel economy.

2. What increase in horsepower should I expect from a K&N replacement filter?

K&N does not complete vehicle performance tests (dynamometer tests) for every application for which we build a replacement air filter. We do complete air flow testing for every air filter, and can verify that a K&N air filter will flow air with less restriction than its OEM counterpart. However, other components of the vehicle's air intake system (like the air filter housing or tubing) can create air restriction and limit horsepower. The design of these parts varies among different vehicles and manufacturers, so there is no way to estimate a certain amount of horsepower gain from just replacing an air filter. The higher air flow and lower restriction will increase performance, but we cannot guarantee a certain/exact amount.

3. What increase in horsepower should I expect from a K&N air intake system?

Dynamometer tests indicating horsepower and torque increases over the OEM intake system will appear on the "Product Details" page for each of our performance intake systems.

4. Can a K&N filter give my engine too much air flow?

No, an engine can only draw in a certain volume of air depending on the engine's bore and stroke, and number of cylinders. A replacement air filter or performance intake system cannot physically increase the volume of air the engine takes in.

5. What is the micron rating and efficiency of a K&N air filter?

Automotive air filters are not rated by micron size, they are rated by efficiency. K&N tests the filtering ability of our air filters using the ISO 5011 test procedure. In general, most K&N air filters will test between 97%-99% efficiency. Some air filters have their air filter test data published in the Available Information section of the product details page for that part number.

6. What are the air filtration requirements for my vehicle?

We are unaware of any vehicle manufacturer having published specific filtration requirements for any of their vehicles. As per the rights guaranteed under the Magnuson-Moss Warranty Act, consumers are free to use any brand of replacement part in their vehicle, without affecting the vehicle's warranty. Having specific filtration requirements would limit consumers' choices, and would not be viewed favorably by the Federal Trade Commission.

7. Some air filter companies tout their high filtration levels in the 99th percentile. Doesn't higher filtration mean a better air filter?

Not necessarily. 99% filtration efficiency is certainly a very good achievement. However, filter efficiency is just one statistic of filter performance which is measured (but is also the statistic most commonly published). The other air filter performance statistics measured are: capacity, restriction, and service life. These other factors reflect the amount of dirt the filter can hold, how easily air can flow through the filter, and how long the filter can be used before servicing. If one particular brand of filter consistently achieves 99%+ efficiency, it would be interesting to know if they also excel in the other performance areas, or are sacrificing one statistic to help increase another.

Given the fact that vehicle manufacturers do not publish specific filtration requirements for their vehicles, it is not strange that we find major, reputable filter brands offering replacement filters with efficiencies varying between 94%-99%. Many K&N filters achieve 98%-99% efficiency, in a product design that offers a longer service life, and much lower restriction than other brands of filters. So, a "better" air filter is really a judgement call, and varies by personal preference.

8. More airflow means you are letting more dirt through, right?

No, not at all. K&N air filters operate using a much different technology than other types of air filters. Most disposable filters are "barrier filters". That is, their filtering media acts as a physical barrier to dust particles, and once a dust particle covers a pore in the media, air can no longer flow through that space. This principle is called "surface loading". K&N air filters are built using a fabric filtering material which absorbs dirt and dust particles instead of physically blocking them. This is a principle called "depth loading". The pores in the material continue to let air flow through as the filter absorbs dirt in the media.

Air Filter Cleaning and Oiling

9. How often and how do I need to clean my K&N air filter?

Air filter cleaning instructions and service intervals can be found at the How to Clean K&N Air Filter Products page.

10. How much oil should I use to re-oil my filter after it is cleaned?

Refer to our air filter cleaning and re-oiling procedure for details on how to properly oil your filter once it is clean and dry. For recommended oil quantity by filter part number, enter the part number in the "Search by Part" box on our Application Search Page and the factory oil amount will be shown.

11. Can I use anything other than K&N cleaner and oil?

We do not recommend using other detergents or solvents to clean your air filter, or other types of oil. Products other than those manufactured by K&N have not been tested and may deteriorate the performance and filtering ability of your air filter.

12. Can I use compressed air to dry the filter faster?

Never use compressed air to dry your air filter. Compressed air will rip and tear the fibers that make up the filtering material. Always allow the filter to dry naturally.

13. Can I use a brush to help dislodge dirt on my filter before cleaning?

Never use a brush to dislodge dirt particles on your air filter. The bristles from a brush can rip and tear the filtering material on your air filter. K&N Power Kleen and K&N Synthetic Air Filter Cleaner are powerful degreasing detergents and will loosen even the toughest, most stubborn dirt particles with no scrubbing necessary.

14. Do K&N air filters come pre-oiled or must they be oiled before using?

First, determine what filtering material your air filter is built with by looking at the Product Specifications on the product details page for your air filter part number on the K&N website.

Synthetic air filters do not use any filter oil at all.

Most cotton air filters come from the factory pre-oiled and ready to install. Certain specialty and racing filters are manufactured as unoiled filters and will be clearly indicated as such. Check the Product Specifications on the product details page for your air filter on the K&N website to see if it requires oil.

Warranty

15. Will using a K&N replacement air filter or intake system void my factory warranty?

No. In the United States, in order for the manufacturer of a warranted product (in this case, a vehicle) to void or deny warranty coverage of a repair due to the use of an aftermarket part (a K&N air filter or intake system), the manufacturer must provide proof (evidence) that the aftermarket part is the cause of the necessary repair. These rights are protected under the Consumer Products Warranty Act of 1975 (also referred to as the Magnuson-Moss Warranty Act).

A warranty is a guarantee or promise made by a manufacturer, and is included with their product at no charge when it is sold as new. "Extended Warranties" are actually not warranties at all, since consumers must pay money to receive their benefits. The proper name for an Extended Warranty is a Service Contract. These contracts may contain exclusions or clauses conditioning their coverages, and these may limit the consumer from using certain products (like aftermarket air filters or performance intakes) on their vehicle. Service contracts are not regulated by the Magnuson-Moss Warranty Act, and once a consumer signs an agreement, they are bound to the terms of that contract. In the event of a vehicle repair, the presence of an aftermarket part (even if it is unrelated to the repair) could void the contract and force the consumer to pay for the repair themselves.

Emissions Legal

16. Are K&N filters emissions legal?

Yes. K&N replacement air filters which install into the OEM filter air filter housing in your vehicle are emissions legal in the United States.

17. Are K&N performance air intake systems or RK-series custom air cleaner assemblies emissions legal in the US?

Performance intake systems are legal for street use in most areas of the United States.

In California, and in specific regions which have adopted California air quality regulations, only CARB-exempt performance intakes are legal for street use.

Check the K&N catalog or website for vehicle applications and specific CARB status for each vehicle and air intake.

General Info

18. Can a K&N air filter be made at the factory for any application?

With over 6,000 individual part numbers available, there is a very good chance K&N has an existing product to meet your filter needs. In the event we do not have an air filter available, you may look into the K&N Custom Filter Program, where we modify existing parts to meet customers' exact needs.

19. My filter came with a tube of sealing grease. How important is it?

If a tube of sealing grease was included with your air filter, the grease must be used during filter installation to ensure a good seal. Use only K&N sealing grease, or lithium-based grease as a substitute. Do not use petroleum based grease, as it may deteriorate the seal on your air filter.

20. Will a K&N filter cause my vehicle's mass air sensor to fail?

No. This is an "urban myth" and has not been supported by any factual evidence. The oil does not come off of a K&N air filter when it is in use, even when over-oiled or in extreme air flow rates exceeding 1000 CF'M.

If somehow K&N air filter oil were to make contact with a mass air sensor, the oil would not cause the sensor to fail. We have intentionally coated mass air sensors with our filter oil, and monitored the sensors' output when installed in daily driven vehicles. These sensors continued to function normally, even after being sprayed and submerged in K&N air filter oil. K&N air filter oil does not cause problems with mass air sensors. More mass air sensor information.

21. Can a K&N product cause my Check Engine Light or Service Light to come on?

It is possible that the Check Engine Light may come on after installing a K&N air filter or performance intake system. This does not necessarily mean that there is something wrong with your air filter or intake. Sometimes, the higher air flow and lower restriction provided by the K&N will uncover an existing mechanical or electronic issue with your vehicle. In rare cases, you may have a K&N product which was manufactured outside of its design tolerances, causing sensors in your vehicle to read data outside of their normal expected values. In either case, the K&N Warranty Department can work with you to narrow down the cause of the Check Engine Light and correct the issue.