Sierra's Synthetic Blend 4-Stroke 25W-40 Outboard Oil combines premium-grade synthetic and mineral base stocks with special additives to meet engine demands in the marine environment.Blended with premium grade synthetic and mineral-based stock combined with superior designed additives formulated for the extreme rigors of the marine environment. Superior corrosion protection. Advanced lubrication for reduction of wear to internal engine components. Minimizes piston ring deposits. NMMA FC-W Certified/API-SL.Key FeaturesOutstanding corrosion protectinReduces wear of internal componentsMinimizes piston ring depositsNMMA FC-W Certified/API-SL