An oil filter subassembly comprises a filter head; an orifice fitting attached to the filter head; and a filter element including a cap attached to the orifice fitting. The orifice fitting includes first and second radially disposed pins and a seal disposed above the pins. The cap includes a central opening having a cylindrical wall, the wall including first and second L-shaped grooves having vertical and horizontal portions, the grooves being oppositely disposed from each other, the horizontal portion including an upper side wall extending upwardly away from the vertical groove portion to provide a cam surface. The cap is configured to compress the seal, thereby to provide a downward bias force on the cap. The pins are configured to move downwardly within the vertical groove portions and positionable within the respective horizontal groove portions, the cam surface tending to push down on the respective pin from the bias force.