Yamalube 20W40 Outboard Mineral 4M FC-W Marine Engine Oil 55 Gallon Drum - LUB-20W40-FC-55LUB 20W40 FC 55 Yamalube 20W40 Outboard Mineral 4M FC W Marine Engine Oil 55 Gallon Drum Yamalube 4M is a mineral based four stroke outboard engine oil that's an approved NMMA FC W formulation specifically for use in the harsh marine environment. The FC W rating, which sets the minimum standard for outboard engine lubrication, corrosion protection, and resistance to potentially harmful effects of oil dilution caused by fuel, provides critical