XPS 25W-40 4-Stroke Semi Synthetic Marine Oil This 25W-40 semi-synthetic oil is designed for 4 stroke sterndrive, inboard, and outboard engines. This marine oil is formulated with premium anti-corrosion additives to stand up to marine weathering. XPS 25W-40 provides superior engine protection by helping reduce wear and resist viscosity and thermal breakdown. This engine oil is compatible with systems that contain super charger and catalytic converters. California Residents WARNING Cancer and Rep