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
    Replacement filter

    Posted by Joe on Aug 10th 2020

    Works great 2nd time I've purchased this product.

  • 5
    Donaldson Blue® 6637 Filter

    Posted by Bob Potter on Jul 23rd 2020

    arrived in 2 days , surprised it did lower egts at idle and pulling hard replaced the regular 6637 with blue and impressed a little more money but worth it .

  • 5
    Just are the best!

    Posted by James Benson on Jul 16th 2020

    Donaldson Blue is just the best. My super duty runs great with the additional air that it is able to get thru the medium. And at a great price. Don't be afraid. Just do it!

  • 5
    Donaldson Blue 6637

    Posted by Patrick Peck on Jun 29th 2020

    Bought this filter to replace my dirty 6637 white filter. It seems to breathe much better . Of course the old one was dirty ... so that may be a factor. I noticed turbo sounds like it spools a bit faster. This is one of the most economical upgrades you can do to your truck . More air in makes happy turbo....

  • 5
    Ultimate 6637 filter

    Posted by Dave Branch on Jun 25th 2020

    Best filter for the 6637 mod!! Clay is the go to guy for 7.3L Power Stroke accessories, thank you Riffraff Diesel.

  • 5
    Air filter

    Posted by Joshua on Jun 19th 2020

    Wont buy any other filters these r the best

  • 5
    Big blue filter.

    Posted by Todd Smith on Jun 6th 2020

    What a great upgrade for the 97 and older obs 7.3 diesels. You can actually feel throttle response performance difference by changing this filter. Runs ah little bit smoother an cooler. Can tell its not struggling like the factory intake system to breath in fresh air. Think my truck loves it more than I did. Lol

  • 5
    In my opinion best filter for 7.3 L

    Posted by Allen kimler on May 5th 2020

    My last one lasted 2years. Great product for a good price

  • 5
    Donaldson Blue

    Posted by Mike J on May 2nd 2020

    Quality product great price