NAPA Gold Oil Filters Provide Excellent Engine Protection Using Conventional, Synthetic, or Synthetic-blended Motor Oils, As Recommended By The OE Vehicle Manufacturer Laboratory Test Performance per ISO 454812: 18 Grams Dirt (NAPA Gold # 1515), 99% Efficient At 23 Microns (Based On NAPA Gold # 1515, 1356, 7060) The K&N Performance Gold® Oil Filter has been constructed from the ground up to satisfy the high performance needs of race car owners and drivers, as well as the average vehicle owner who wants the very best oil filter available. Our oil filter's efficiency rating meets or exceeds the requirements of high performance automotive engine builders. OE FIX Guide, Volume 2. The latest edition of our award-winning magazine features 24 pages of our latest innovations you can't get from the OEM, all designed to save time, cut costs and increase reliability. Articles Technical Articles . Check out our articles that answer your everyday questions about oil, viscosity and other related subjects. New articles are highlighted in red color.