Synthetic blend 25W-40 engine oil is formulated for stern drive & inboard marine engines with catalyst emission systems. Sierra synthetic blend catalyst inboard engine oil SAE 25W-40 5 quart jug Recommended for use with inboard and I/O marine engines with catalyst exhaust systems Meets the requirements of modern 4-stroke recreational inboard, I/O, and outboard engines with or without emission catalyst systems Developed specifically for the marine environment and the high running stresses marine engines encounter Protects internal engine components from rust and corrosion Features high detergency, antiwear proprties, and dispersants to prevent engine sludge ZDDP anti-wear additive prevents phosphorus depletion and extends the emission catalyst life NMMA FC-W certified/API-SL Replaces Mercury 92-8M0078630