will a K&N filter affect my vehicle's fuel economy?
- There is a relationship between air filter restriction and
mileage. The theory behind this is simple, the harder an engine
has to work to suck air through the intake tubes and air filter,
the more gas gets wasted in the process. Many K&N users
report an increase in their fuel economy after beginning to
use our air filters, as noted on our testimonial page. However,
these experiences do not mean you will also experience a change
in your mileage. We certainly understand why it is theoretically
possible for a consumer to experience a mileage increase after
installing a K&N air filter or intake system, however, we
do not go so far as to make a general claim that our air filters
and intake systems will provide an increase in mileage. It is
virtually impossible to make sweeping and general claims about
mileage. Even the EPA fuel rating numbers for new cars are often
not representative of the mileage you actually experience. There
are many variables that affect mileage such as: tire inflation,
the type of fuel, weather, elevation, the speed at which you
drive, the gear in which you drive, the speed with which you
accelerate, engine maintenance, excessive idling, cruise control,
the grade of motor oil you use, and of course, the condition
of your air filter. In short, mileage is complicated. K&N
filters are less restrictive than disposable paper or synthetic
air filters and K&N Intake Systems are less restrictive
than the factory installed air path. So K&N filter technology
could be an important tool, when combined with other elements,
to help keep mileage as high as possible.
Oh yeah, there's one more limitation imposed by science. If
you take advantage of added power by driving more aggressively,
you will reduce mileage. You cannot have your cake and eat it
increase in horsepower should I expect from a K&N replacement
- K&N direct replacement filters which install into your
vehicle's factory air box can provide an increase of between
1 and 4 horsepower. Results will vary depending on your vehicle,
driving habits, load on the engine (towing for example), existing
air system restriction, and other factors.
increase in horsepower should I expect from a K&N air intake
- K&N makes several different types and configurations of
performance air intake systems. Depending on the year, make,
and model of your vehicle, only one style of intake system may
be available for that vehicle. All of our intake systems are
dyno-tested and guaranteed to increase your vehicle's horsepower.
Instead of making a general claim, we publish estimated intake
system horsepower increases for many part numbers and vehicles.
To see estimated power gains of specific air intakes for specific
vehicles, enter the part number in our part search or look up
a specific vehicle in our application search.
often do I need to clean my K&N air filter?
- If you have not experienced a decrease in mileage or engine
performance, chances are your filter is fine and does not yet
need cleaning. To be more specific, the filter does not require
cleaning if you can still see the wire screen on the entire
air filter regardless of how dirty it may appear. When the screen
is no longer visible some place on the filter, it is time to
clean it. When used in normal paved road, street or highway
conditions, our replacement air filters that fit in the factory
air box should require cleaning every 50,000 miles and our large
conical filters on an intake system should require cleaning
every 100,000 miles. When used in dusty or off-road environments,
our filters will require cleaning more often. We recommend that
you visually inspect your filter once every 25,000 miles to
determine if the screen is still visible.
can I tell the size of the engine in my vehicle?
North America: Most vehicles have an emissions decal placed
either on the backside of the hood, on the radiator core support,
or on the air box (the box that holds the air filter in place).
Your engine size should be shown on the decal (4.0L for example).
If you can't find the emissions decal you may also find the
engine size printed on the decal under the hood that shows
your engine's belt routing. You may also write down your Vehicle
Identification Number that is stamped visibly near your driver's
side dashboard top and listed on your vehicle registration
certificate. This number can then be entered on K&N's
part search by VIN webpage to find engine size as well as
products for your vehicle. You may also contact your local
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 size (measured by such things as bore, stroke
and number of cylinders). Vehicles are designed to accommodate
large changes in air pressure so they can operate at sea level
or at an altitude of 14,000 feet. Engine computers adjust
the amount of fuel required as a result of changes in air
pressure (density). Air filter restriction when the filter
is new and especially as the filter loads with dust will result
in lower air pressure and availability similar to being at
a high elevation. High-flow air filters that were invented
by K&N were designed to reduce the work necessary to pull
air through the filter and to increase air pressure. Increased
air pressure is one of the key elements in producing more
using a K&N direct replacement filter void my factory
- It is against federal law in the United States for a manufacturer
to require the use of a specific brand of air or oil filter
unless it provides a replacement air or oil filter, free of
charge, under the terms of the vehicle warranty. For a more
thorough discussion of this law known as the Magnuson-Moss
Warranty Act, see our Vehicle Warranty Section of our Air
Filter Facts page, and our Letter Regarding Vehicle Warranty
and K&N Replacement Filters.
installing a K&N performance intake system void my factory
- Most K&N air intake systems are warranted for 1,000,000
miles which exceeds the warranty offered on the original factory
intake system. The installation of an air intake system should
not void your factory warranty. It is never a bad idea to
contact your local dealership and ask them before purchasing
the new K&N system whether they will object. If they tell
you an air intake system will void your vehicle warranty,
please contact us and we will speak with the dealership directly
to clear up the misunderstanding. Another idea would be to
contact a different dealer who may have a different policy
since many dealerships actually sell K&N intake systems.
As an additional level of comfort, we also offer our Consumer
Protection Pledge. It takes customer service to an even higher
level by giving you confidence that when you buy K&N you
get on-going support from a team of professionals who will
talk directly to dealerships to resolve any questions that
may come up.
K&N air filters come pre-oiled or must they be oiled before
- Almost all K&N air filters come pre-oiled and ready
to use. The filter oil we use is red. A new oiled filter will
appear red-pink in color. Some crankcase vent air filters
come unoiled, however, they come with a small packet of K&N
filter oil so they can be oiled before use. There are also
a limited number of filters with specialty uses which are
not pre-oiled. These items will be clearly marked as unoiled.
Using an unoiled K&N filter will greatly reduce the filter's
efficiency and void our product warranty on filters that come
pre-oiled from the factory. If you receive a filter that is
packaged in its cellophane wrapper and is unoiled, contact
K&N's Customer Support department at (800) 858-3333.
a K&N air filter be made at the factory for any application?
- K&N has an active Custom Air Filter Program to meet
the needs of consumers with special filtration needs. We offer
thousands of possible configurations of custom filters, in
different shapes, dimensions and heights. Click here to read
filter came with a tube of sealing grease. How important is
- It is rather important. It helps to maintain a seal on an
uneven air box surface. If sealing grease is unavailable,
white lithium or synthetic grease will work just fine. Petroleum-based
products are not recommended.
K&N filters emissions legal?
- All K&N direct replacement filters are emissions legal.
They perform the same function as other types of disposable
filters and fit right into the factory air box. K&N's
custom, universal or conical air filters are not legal for
street use in California or other states that have emission
control standards. However, if the intake system you are attaching
a K&N cone filter to is CARB exempt, the K&N cone
filter will not change that status and will be part of the
exempt system. Check your local laws if you are unsure what
modifications may be allowed on your vehicle.
K&N performance air intake systems emissions legal in
- All intake systems are legal in most states because most
states do not have regulations governing them. So this question
really has to do with California and other states that have
emission control standards. In order for an intake system
to be legal in these states, it must receive an Exemption
in the form of an EO number from the California Air Resources
Board (CARB). To further complicate matters CARB exemption
is issued only for specific part numbers used on specific
vehicles. That means a part number can be CARB exempt for
some vehicle applications and not others. There is no such
thing as CARB Pending. A particular part number on a particular
vehicle is either exempt or not. The best way for you to determine
the status of the part number you are interested in for your
vehicle is to look up the intake systems available for your
vehicle in our vehicle/part search engine and check for CARB
exemption. If you are unsure whether CARB exemption is required
for a part to be legal in your state, check with your local
or state motor vehicle or emissions agency.
K&N RK-Series Custom Air Cleaner Assemblies emissions
- The rules for motorcycle intake kits are the same as for
air intake systems. Please refer to Question 13 above. Some
RK-Series assemblies for specific motorcycles have received
CARB Exemption, others have not. The best way for you to determine
the status of the part number you are interested in for your
motorcycle is to look up the parts available for your motorcycle
in our vehicle/part search engine.
How do I clean a K&N air filter?
- Use a K&N Filter Care Service Kit, available at all
major auto parts stores and a low pressure nozzle-free garden
hose. A filter cleaned with K&N cleaning products will
ensure a lifetime of performance from your air filter. Instructions
for cleaning your K&N air filter are on our Air Filter
Cleaning Instructions page.
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.
I use anything other than K&N cleaner and oil?
- For best results, we recommend that you use K&N air
filter oil and K&N air filter cleaner. K&N air filter
oil is a special compound which forms a very efficient tacking
agent that helps capture dust. Our cleaner is a non-detergent
degreaser. Petroleum products such as transmission fluid and
motor oil will soften and destroy the rubber sealing edges.
Harsh solvents and gasoline will harden the rubber seals causing
the filter to distort (shrink). A mild detergent can be used
in a pinch, but care should be taken to fully rinse it out.
Rinsing detergent out of a filter is similar to getting soap
out of a sponge; it's not that easy to do. Always make sure
the filter is dry before re-oiling.
I use compressed air to dry the filter faster?
- No, this can blow the filter material right out of the wire
mesh and ruin the filter. Pick a nice day to clean the filter
and let it dry naturally. A low pressure air flow such as
from an industrial drying machine or blow dryer will help
the filter dry more quickly.
I brush the wire screen with a toothbrush to get all the "crud"
- No, this could tear up the cotton gauze.
is the micron rating and efficiency of a K&N air filter?
- Air filters are not measured by micron size. As an industry
standard, air filters are tested in accordance with the ISO
5011 test protocol to measure capacity (the physical amount
of dust a filter can hold before cleaning is necessary) and
efficiency (the filter's ability to trap and hold dust). See
technical service bulletin 89-5R from the Filter Manufacturer's
Council. The dust selected for the test contains a specified
distribution of different particle sizes according to ISO
The content of the two most commonly used types of ISO test
dust for air filters is as follows:
COARSE TEST DUST
FINE TEST DUST
Size in Micrometers (Microns)
by Volume (+/- 3%)
Size in Micrometers (Microns)
by Volume (+/- 3%)
has demonstrated that on average, K&N replacement air
filters and air intake systems have a cumulative or Full Life
filtration efficiency of between 96 and 99%. Different filters
test at different efficiencies due to changes in their shape,
surface area and relationship to the direction of air flow
through the factory air box or test housing. Like most air
filters available in the USA, our filters will provide all
the engine protection you need.
are the air filtration requirements for my vehicle?
- There is no published requirement for vehicle filtration.
Car and truck owner's manuals are silent on the issue and
you will find very few companies that even credibly discuss
filtration efficiency. We believe this demonstrates that most
air filters sold today provide adequate levels of filtration.
Particularly when compared with the filtration provided by
fuel and oil filters.
airflow means you are letting more dirt through, right?
- No. Filtration testing measures the percentage of dust retained
before the filter reaches a terminal test pressure, often
10" of restriction above initial restriction. We use
airflow as a simplified term to explain a more complicated
physical process. The more precise description is restriction:
K&N air filters create less restriction which helps an
engine run better. An engine will only use the air it needs
and our air filters do not result in an engine using more
air than necessary. Rather, they result in the engine experiencing
less restriction. The terms airflow and restriction are inversely
related. Our air filters provide either less restriction at
a fixed airflow rate; or more airflow as a fixed level of
restriction. In neither case is more air being used than necessary.
I know the dimensions required, do you have a clamp-on air
filter for my special application (snowmobile, tractor, small
- We have a powerful tool we have developed for just that
purpose. You can search our filter catalog by dimension and/or
shape on our Filter by Dimension Search page. We make hundreds
of specialty, custom and racing filters for just about any
need. These specialty filters come in many shapes, dimensions
and sizes. Some of them have angled or offset flanges to fit
unique space requirements. Another way to browse through our
specialty, custom and racing air filters is to visit our universal
air filter page. If none of these meet your needs our Custom
Air Filter Program may be able to help.
I install the largest K&N filter that will fit in my race
- If an existing K&N filter is large enough to provide
negligible restriction, a larger than required filter will
not affect the amount of air an engine can take in, however,
it will lengthen the filter's service interval. A longer service
interval can be an important factor when racing in dusty,
a K&N filter cause my vehicle's mass air sensor to fail?
- No, it is both impossible and ridiculous.
It is impossible because we know that the oil treatment on
our cotton is very small (usually less than 2 ounces). Once
the oil is properly and evenly absorbed through the cotton,
no oil will come off, even under extreme engine conditions.
It is ridiculous, because no dealership or service provider
has ever been able to provide us with evidence to support
this "myth," and in fact, our investigations have
revealed that even authorized dealerships are simply speculating
and do not have the test equipment necessary to know whether
the sensor has failed or why. It is even more ridiculous because
some car manufacturers use and sell air filters treated with
oil on a regular basis. There are also major brands of disposable
air filters that are treated with oil. We all use oil for
the same reason, it helps in the filtration efficiency of
an air filter. For more information on this topic including
videos, see our Mass Air Flow Sensor Statement page. Out of
the millions of air filters we sell, we only receive a handful
of consumer complaints each month that a dealership or service
provider has blamed a vehicle sensor repair on our product.
We take each complaint very seriously and see it as an opportunity
to stop a consumer from being taken advantage of. We investigate
the situation thoroughly and take full responsibility for
resolving the issue. For more information on how we educate
and persuade the service provider to reconsider their position,
see Mass Air Flow Sensor Information & Testing. We are
so confident in our ability to resolve these situations and
to help a consumer fight back that we offer our Consumer Protection
Pledge. As a result of our standing up for consumer rights
and providing assistance to resolve a disagreement, we have
had over 300 actual sensors sent to us by dealerships who
claimed our product had caused them to fail. Microscopic,
electronic and chemical testing revealed that none of the
sensors were contaminated by K&N oil (K&N Detailed
MAF Sensor Test Results). What is perhaps the single biggest
clue to what is going on is that over 50% of these sensors
were not broken in the first place for any reason. Click here
for more information on how this may happen.
a K&N product cause my Check Engine Light or Service Light
to come on?
- A properly installed K&N product should not cause the
Service Light to illuminate. For more information see our
Engine Service Lights and K&N Products page.