Oil Filter; The polyester content enhances the strength of the media to withstand extended exposure to hot engine oil. Anti-drain back valves are included to help prevent dry starts. Anti-drain back valves that are made of silicone provide cold/heat resistance (down to -75 F and up to 450 degrees F). The only parts recommended by Ford Motor Company for Ford, Lincoln, and Mercury vehicles. Robust steel center tubes and lock seam design withstands pressure surges and help prevent leakage. Bonded end plates help keep consistent pleat spacing. Steel case is painted for rust resistance. Flutes aid filter removal process. End cap seam is crimped and rolled for a good seal. Motorcraft Filters align to the SAE US/Car 36 engineering requirements. Motorcraft filters provide excellent protection for today's longer service intervals. Large filter media area provides optimum filtering efficiency throughout the oil change cycle; 80 percent efficiency on particles 20 microns or larger, Cellulose and polyester blend media is formulated for high capacity and strength. Filters with an S suffix denote a silicon-based anti-drain back valve. Pressure relief valves help maintain supply of oil to the engine under extreme cold conditions or if the filter gets clogged. Location of relief valve in the majority of Ford application filters prevents settled debris from entering and potentially damaging the engine.