Donaldson Blue® 6637 Filter

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(You save $13.39 )

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


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  • 5
    Donaldson Blue 6637

    Posted by Robert on Jan 13th 2020

    7.3 breaths better! Quick and easy upgrade!

  • 5
    Donaldson filter 6637

    Posted by Jesus Ramos on Jan 12th 2020

    The filter is excellent for my 2002 F250 7.3

  • 5
    High quality

    Posted by Jake on Jan 6th 2020

    Can't say I've noticed a huge difference between the regular and this one, but I'm also on tired injectors, no tunes and have boost/exhaust leaks I need fixed first. However it's a high quality filter and I will purchase this again over the AFE or the regular 6637.

  • 5
    Donaldson Blue 6637 Filter

    Posted by David Rogers on Dec 24th 2019

    This filter really let my engine breath a large amount of air. I also mike the fact that the media is hydrophobic. I will definitely buy this filter from RiffRaff again.

  • 5
    Great FIlter

    Posted by GW on Dec 9th 2019

    Bought this to replace one of the larger Dondaldson BHAFs in my Dodge for better hood clearance. Very pleased with this compared to the paper element filter it replaced. Hoping the synthetic media will last longer than the paper since I was replacing the filters due to age degradation rather than flow restriction (truck is driven ~5k miles per year).

  • 5
    Excellent Product

    Posted by James on Dec 6th 2019

    Excellent Price

  • 5
    New Air Filter

    Posted by David Smith on Dec 2nd 2019

    Great quality filter. My truck loves it.

  • 5
    Air filter

    Posted by Wayne Neece on Nov 7th 2019

    Just what I wanted

  • 5
    Donaldson Blue

    Posted by Max on Oct 2nd 2019

    Great Filter! Great Price! Riffraff is the Best
    for OBO Powerstroke products!