Full flow filter

A full flow fluid filter 300, Fig. 15 has a housing 302 extending axially along an axis 304, and a pleated filter element 318 having a plurality of pleats in a closed loop annulus having an outer perimeter 320 defined by a plurality of outer pleat tips, an inner perimeter 322 defined by a plurality of inner pleat tips, and a hollow interior 324 extending along the axis. Fluid flows substantially directly axially through the filter element, with minimal bending and change of direction, minimizing flow restriction.