Wix Filter/NapaGold Oil Filter vs Purolator

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  • Purolator uses a leaf spring rather than a coil spring; the leaf spring must always seat properly onto the end cap. Additionally, a leaf spring can bend under high pressures.
  • Purolator uses metal end caps rather than the fiberboard end caps.
  • The filter media inside the Purolator was crimped to itself, rather than glued, and a string was loosely tied around the media.
  • Purolator uses a phenolic resin which helps to bind the media and protect during high temperatures.
  • The center tube of the Purolator filter is a spot-welded, straight seam; other brands use a spiraled center tube for better flow.
  • The Purolator filter uses a silicon anti-drain back valve which is less likely to break down than the nitrile rubber valves. The anti-drain back valve is used to prevent oil from draining back to the crankcase after shutdown.


  • We found excessive amounts of glue over the end caps.
  • The Purolator was the shortest of all the filters.
  • The Purolator had the most number of pleats at 67, but the pleats were wavy.
  • The Purolator filter tied the Bosch filter with the longest media at just over 101 inches.
  • The Purolator filter had the most media area at 384 square inches.