ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Today's Car Air Filters

Updated on June 26, 2012

Paper vs Oiled

Like many of us I was somewhat ignorant about today's car air filters. Ten years ago as part of my job I got involved in industrial air systems, I had visits by multiple salesmen trying to get me to buy their product and providing various literature and technical data.

Most oil soaked panel filters have smaller media areas than the original paper units, as a result, to attain a lower pressure drop they offer less resistance by virtue of passing more dirt. Once theca's air filter starts to collect dirt on its surface it increases its filtration properties but also loses the original benefit in terms of pressure drop or flow. The smaller media area means it takes a shorter time for the filter to become clogged to a point where there is a noticeable loss in performance. Also for a given volume of air the velocity of the air through a filter is determined by the area of the filter, a smaller area requires a higher velocity. Higher velocity creates more risk of the oil migrating or the dirt passing through as the tiny oil droplets can be squeezed through the filter pores. Another interesting fact about oil is that it tends to attract to other particles rather than staying in droplet form. As a result, the droplet size is unlikely to stay fine and therefore the available capture area for dirt diminishes. This is why oil type filters have such short service intervals. In fact its more than likely than the gains offered by a K & N and other manufactures are only for the first few thousand miles, particularly in dusty or dry months, when the dirt builds up quicker. Basically, the pressure drop across a filter (i.e. restriction to air flow) is based on three things... the size of the media area, the filtration rate and the volume of air its trying to filter.

As the volume of air increases through the filter with engine speed, so does the resistance or pressure drop, that is why a static test on an air filter (i.e. when fixed on a rolling road) doesn’t give a true figure in terms of horsepower, as the car isn’t moving through the air and creating additional upstream pressure into the filter. There is no doubt that an oil lubed filter will give a lower pressure drop, compared to a standard one but when the car is actually moving the gains are probably less significant as the dynamics come into play. As the car starts to travel at higher speed there is additional force applied to the filter up-stream which can cause the oil to migrate through the filter as a liquid and will naturally travel in the direction of the air. If the oil particles are then blown out of the filter they can then find their way onto the MAF (mass air flow) causing the device to read incorrectly. The inlet on an air cooled and some German designed engines already has a fine oil mist by virtue of an air oil separator unit.

Now onto the issue of dust particles, yes its correct that all filters will pass some dirt, and the standard filter even does this, but what is important is both the size and the amount. Anyone that has emptied a vacuum cleaner bag will know how fine dust can clog and be a real issue, so any filter that passes dust as a sacrifice for performance isn’t a good compromise. The dust finds its way into the throttle body and the MAF (mass air flow) building up a black tar like deposit and also into the engine on the valve stems. In itself the dust is harmless, and can be cleaned (where accessible) however, if the filter is damaged during cleaning larger particles could enter the engine and do more serious damage.

I have K & N filters on two of my cars and have not had any significant engine issues with regular cleaning of the filter and occasional cleaning of the MAF (mass air flow sensor). Unless you are a keen DIY mechanic and can fix cars, clean throttle bodies and MAF's yourself I would suggest that the gains of fitting a K & N are not worth the additional maintenance.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)