Bought a NAPA Silver oil filter to try today (KCJEEP recommendation) for my Jeep 4.0L ... I was surprised at the construction : Metal end caps , coiled steel spring , steel canister , Nitrile gasket and good filter media . The interesting thing I noticed was the combo anti-drain back / pressure relief valve which is a bit unique - all for only $3.66 ea. ... For a 3,000 ~ 4,000 mile conventional oil OCI I hope it does well .