An oil filter specifically for Subaru horizontally opposed engines, with improved filtration accuracy while retaining the same pressure loss. The optimal balance of pressure loss and filtration performance is set specifically for Subaru. A high-strength perforated plate inside the filter maintains stable filtration with high-viscosity oil and high oil pressures during sporting driving. The anti-drainback valve and body seal (mounting-face gasket) use nitrile rubber with excellent low-temperature and oil resistance to prevent oil leaks and seepage. Using it with the ZERO SP engine oil series can draw out further performance from Subaru horizontally opposed engines.