Duramax CAT Oil Filter Conversion Kit



Product Details



Using the new MDDP filter nipple on your factory oil filter assembly, you can run the CAT 1R-1807 filter, giving you best filtration on the market utilizing the factory oil filter location. With this kit you can add a whole extra QUART to your oil capacity making it 11 quarts!

NOTE: This will NOT FIT 2020+ L5P TRUCKS due to the smaller filter housing change. 


The Cat 1R-1807 filter starts at 4 microns @ 20% efficiency and at 20 microns at 100% efficiency.  On top of filtration it has about THREE times more filtering media.  The Cat media is 2.11 times longer and the pleats are 1.13 deeper making the Cat filters area 2.39 larger than the factory ACDelco filter media.

When the small OEM sized filter is not able to flow the amount of oil needed to flow through it, there is something called a bypass valve that is used.  Every factory and factory replacement Duramax filter will have this bypass valve.  The CAT 1R-1807 filter does not have this valve as it is a true flow filter.

This valve sits at the bottom of filter casing.  When the filter cannot flow enough oil through it, the value opens up and sends dirty, unfiltered, liquid sandpaper through your engine.  This can lead to sucking up and throwing all the dirt and tiny metal shavings through expensive parts such as the oil pump, crank journal bearings, turbo journal bearing, cylinder walls, cam shaft, rocker arms, etc..  When does this bypass valve open? We don't know.  Does it open at 4,000 miles, 7,000 miles, high oil pressure when cold, or does it open at all?


  • CAT 1R-1807 Oil Filter
  • MDDP Filter Nipple
  • 1/2" Internal Pipe Wrench
  • 5.5" MDDP Decal
  • Instructions


  • 2001-2019 Duramax Years
  • Reviews

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