This is an FC-W oil produced by Yamaha for their high powered four-stroke engines. The oil is an SAE 10W-30 oil that provides protection during cold starts and operating the engine with heavy loads. The oil has an additive that fights corrosion and the wear and tear associated with marine outboards. The 4M-FC-W oil also resists foaming at high speeds. Foaming can degrade an oil's lubricity.