This manual covers Mercury Mariner Optimax DFI Optimax outboard engines manufactured between 2000 and 2005. These V6 engines, available in 115 HP, 135 HP, 150 HP, and 175 HP configurations, feature a 2.5L displacement and Direct Fuel Injection (DFI) technology for enhanced performance and efficiency. Designed for reliable operation on a variety of watercraft, the Mariner Optimax series is engineered for durability and power. This comprehensive service and repair manual provides essential information for maintaining and troubleshooting your Mercury Mariner Optimax engine. It details routine maintenance procedures, including recommended fluids and fuel types, as well as technical specifications for engine components and electrical systems. By following the guidelines within this manual, owners and technicians can ensure optimal performance, longevity, and safe operation of their Mercury Mariner Optimax outboard.