Abstract: A diesel engine secondary oil filter is formed from a punched tinned steel spiral lock seam center tube, with a flanged cap at one end and a flanged threaded outlet at the other end. A layer of polyester non-woven media is wrapped in one wind around the center tube. A yarn is wound is a 27-diamond pattern in a first yarn section out to two inches outer diameter. The yarn is tied off. Knitted socks are first placed partially on axial ends of the first wound section, leaving half of the socks extending over the ends. A sheet of activated carbon paper about 1/6 of an inch thick and about 52 inches long is rolled onto the filter cartridge with about nine turns. The carbon paper is made of a cellulose paper impregnated with about 50% activated carbon powder by weight.