Sierra's Premium Blend 25W-40 catalyst engine oil is specially formulated to meet the needs of 4-stroke marine engines with catalyst emission systems. Sierra premium blend catalyst compatible inboard engine oil SAE 25W-40 1 quart bottle Recommended for use with inboard and I/O marine engines with catalyst exhaust systems Meets the requirements of modern 4-stroke recreational 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, corrosion, and from sticking piston rings Premium blend features high detergency, anti-oxidants, and antiwear proprties ZDDP anti-wear additive prevents phosphorus depletion and extends the emission catalyst life Exceeds all 4-stroke requirements including FC-W and FC-W Cat compatible NMMA FC-W certified Replaces Mercury 92-8M0078627, 92-8M0078629 Replaces Bel-Ray 99730-BT1