Donaldson Blue® 6637 Filter

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Donaldson Blue® 6637 Intake Filter for Ford 7.3L 94-03

Donaldson Blue® air filters with Ultra-Web® nanofiber technology protect engines by providing better initial and overall efficiency compared to conventional cellulose media. Donaldson invented air filters for heavy-duty diesel engines over 100 years ago and were the first to develop nanofiber air filter media for the diesel engines, with more than 20 years of proven performance. 

  • Longer Engine Life - Donaldson Blue™ air filters provided better engine protection by allowing much less contaminant to pass through than cellulose air filters but still maintaing a higher flow rate
  • Longer Filter Life - Smaller interfiber spaces of Ultra-Web® nanofiber technology hold more submicron contaminant than conventional filters with cellulose media, delivering longer filter life
  • Increased Flow - Utilizing the nanofiber Ultra-Web® media has allowed for a 37% increase in flow over the standard 6637 cellulose filter. It has also been tested to flow over 1300 CFM+.
Media Type
  • Ultra-Web® Nanofiber Technology -- Exclusively in Donaldson Blue air filters
    • Engineered to perform in extreme temperature and humidity conditions, unlike ordinary nanofibers and cellulose which aren't hydrophobic
    • Proven in the real world – used in diesel engines for nearly two decades
    • On-road applications are guaranteed to go twice the distance compared to standard cellulose filters

We suggest buying them in quantities of 2 as your shipping won't increase much and you will save money.

100% Made In The USA


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  • 5

    Posted by hank on Oct 4th 2018

    What a difference. I took of my Napa wix and but then on and I can feel and hear the difference. Plus less smoke! Home run.

  • 5
    Another Excellent Product

    Posted by TK on Sep 3rd 2018

    Excellent long-standing brand product sold by an excellent business!
    Thanks Riffraff!

  • 5
    Best filter for the buck

    Posted by Brian S on Aug 28th 2018

    I always buy the blue Donaldson filter it’s resistant to water which makes cleaning the engine bay a breeze it goes with my truck, and really they keep dirt out very well I usually buy one every 15k miles

  • 5
    More turbo whistle

    Posted by Andrew on Aug 27th 2018

    My 7.3 sounds happy now.

  • 5
    Best Filter For Your 7.3

    Posted by Unknown on Aug 10th 2018

    I previously bought an $$ S&B filter kit with the big intake box. The replacement filters were expensive and the big box really made accessing the powersteering reservoir a real pain. Pulled that out and replaced it w a battery tray and this Donaldson filter. Superior filter at a better price and now lots of room under the hood without that plastic intake box. Riff Raff is the place to buy from a great prices and fast shipping and excellent customer service.

  • 5
    Blue 6637

    Posted by Unknown on Aug 7th 2018

    Nice filter for the price.

  • 5
    Best 6637 filter diy intake

    Posted by James on Jul 30th 2018

    I am a fan ... Feel the mpg gain but I believe it lasts longer and cleans the air better. I only buy the blue and only riffraff sells it.

  • 5
    Great in dusty conditions

    Posted by Unknown on Jun 30th 2018

    The filter last a long time in dusty arizona conditions, and wont pass abrasives like some other oiled filters.

  • 5
    Does the job better

    Posted by jerrod thomas on Jun 26th 2018

    Replaced a standard 6637 with this hi flow filter. Looks as good as it performs.