Sierra FC-W 10W-40 4-Stroke Semi Synthetic Marine Oil Sierra 10W-40 FC-W 4 Stroke engine oil is a semi synthetic blend that has been formulated to provide superior protection for outboard engines. The proprietary blend of conventional with synthetic lubricants allow this oil to keep your engine running smoothly under high loads and running stresses. Do NOT mix with gas. Not for use in 2 cycle pre-mix, injected engines, inboardssterndrives equipped with catalytic converters Features Semi Syntheti