Donaldson Blue® 6637 Filter

Part Number:


(You save $14.39 )

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


Write a Review

102 Reviews Hide Reviews Show Reviews

  • 5
    this filter sounds like it flows well,

    Posted by Jason Schrader on Feb 8th 2021

    best price i could find

  • 5
    Great Filter

    Posted by Grant Mott on Jan 3rd 2021

    Swapped to this from a Napa wix and I am really impressed. Almost all smoke on acceleration is gone, and I seem to be able to spool up quicker.

  • 5

    Posted by Dave J on Jan 2nd 2021

    Replaced the old DuraLite on my 97. Super nice filter and a great price.

  • 5
    Way better

    Posted by Unknown on Dec 17th 2020

    Really opened up my truck and let that Garret turbo scream!

  • 5

    Posted by Robert on Dec 2nd 2020

    The best air filter to a 7.3 powerstroke by far!

  • 5
    Donaldson filter 6637

    Posted by Jesus Ramos on Oct 23rd 2020

    Great filter for my 7.3 2002 F250

  • 5
    Great filter

    Posted by Joe on Oct 5th 2020

    Installed on a '99 7.3
    This filter definitely SOUNDS like it flows more than the regular white Donaldson. I buy these from now on. Turbo wheel is still squeaky clean and haven't had an issue

  • 5
    sweet deal on a new air filter

    Posted by Kaiah McLaughlin on Sep 24th 2020

    Yeah buddy, just to clarify the filter sold at napa is not even remotely close to the quality of the Donaldson that you get from riffr-aff. And you can get the pre-filter and air filter delivered for less than the nappy dugout by itself and shipping was over $15 for me. And it was on my doorstep 2 days from the time I placed my order. My main driver (03-7.3l built to the hilt) is now going to be getting all its needs filled by riff raff!!. Thanks guys for you and your services, warms my heart knowing there are good people still in the area I was born and raised. God bless and take care, I'll be back for more lickity split.

  • 5
    Perfect fit. Used on my 2001 Excursion 7.3l.

    Posted by Mark C. on Aug 26th 2020

    Replaced same. Had been on Excursion for just about 2yrs. As usual Clay is awesome.