🏷️ Basic Information Identification Make: Mercury Model: Optimax Year: 1998-1999 Generation: Optimax DFI 📋 Manual Details Publication Manual Type: Service Manual / Repair Manual Language: English Format: PDF Availability Delivery: Instant Download ⚙️ Engine Specifications General Engine Type: Direct Fuel Injection (DFI) Engine Configuration: V6 (Implied by common Optimax configurations) Engine Displacement: Not Specified (Commonly 2.5L for these models) Performance Power Output 135Hp: 135 HP Power Output 150Hp: 150 HP Fuel System Fuel System Type: Multi-point Sequential Electronic Fuel Injection Recommended Fuel: 87, 91, 92, 93 Octane; Race Gas Cooling System Cooling System Type: Water Cooled Ignition Ignition Type: Electronic Spark Plug Type: Specified in manual Engine Internals Engine Valvetrain: DOHC Lubrication Lubrication System Type: Wet Sump Thermodynamics Thermostat Operating Temperature: Specified in manual 🔧 Transmission Gear Ratio Gear Ratio: Specified in manual Gears Gears: Forward-Neutral-Reverse Propeller Rotation Propeller Rotation: Right-hand rotation (Standard) Counter Rotation Available: Yes (Implied by 'Propeller Counter rotation' mention) Lower Unit Lower Unit Gear Oil Capacity: Specified in manual (ml) 📐 Dimensions Physical Transom Height: Specified in manual Overall Length: Not Specified Overall Width: Not Specified Weight: Not Specified 🔧 Maintenance Intervals Service Interval Recommendations: Follow Maintenance Schedule Fluids Engine Oil Change: Procedure detailed Gear Oil Change: Procedure detailed Components Spark Plug Maintenance: Procedure detailed Water Pump Impeller Replacement: Procedure detailed Fuel Filter Replacement: Low Pressure and High Pressure detailed Adjustments Idle Speed Adjustment: Procedure detailed Tappet Clearance Adjustment: Procedure detailed Diagnostics Troubleshooting: Covered in relevant sections Safety Anode And Bonding Wire Maintenance: Procedure detailed Performance Tuning Ignition Timing Adjustment: Procedure detailed Carburetor Adjustment: Procedure detailed (where applicable) Efi System Diagnosis: Covered in manual Electrical System Battery Charging System Testing: Procedure detailed Starter Motor Testing: Procedure detailed Wiring Diagrams Included: Yes Engine Rebuild Powerhead Rebuild: Comprehensive procedures Mid-Section Rebuild: Comprehensive procedures Lower Unit Rebuild: Comprehensive procedures Gear Shim And Adjustment: Procedure detailed