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Mercury | 300 Hour Service Kit | 8M0120867

Stay on schedule with a complete 300 hour service kit for Mercury 8 HP and 9.9 HP carbureted (209cc) four-stroke outboards equipped with Command Thrust/Bigfoot gearcases. Built around 25W-40 four-stroke engine oil, this bundle covers the most common milestone service items—engine lubrication, gearcase service parts, fuel filtration, cooling components, ignition parts, and corrosion protection—so you can keep your small outboard performing reliably season after season.

Serial number range: 0R042475 & Above

What’s Included in This Kit

• 1 x 25W-40 Four-Stroke Engine Oil (Quart)
• 1 x Gear Lube (Quart)
• 1 x Fuel Filter
• 1 x Oil Drain Seal
• 2 x Gearcase Drain Seals
• 1 x Thermostat
• 1 x Thermostat Gasket
• 2 x Spark Plugs
• 1 x Water Impeller Kit
• 1 x Anode

Why This Kit Makes Service Easier

• Milestone coverage: Combines fluids, seals, filters, cooling parts, and ignition components in one kit.
• Cooling system refresh: Thermostat and impeller service helps maintain proper water flow and stable operating temperature.
• Fuel-side protection: Replacing the fuel filter helps reduce debris and contamination reaching critical components.
• Corrosion defense: Includes an anode to help reduce galvanic corrosion in marine environments.

Service Notes

• Designed specifically for Mercury 8/9.9 HP models with Command Thrust/Bigfoot gearcases.
• Replace drain seals during every service to help maintain a proper seal.
• Dispose of used oil and gear lube according to local regulations.

FAQ

Does this kit fit standard gearcase models?
No. This kit is intended for Command Thrust/Bigfoot gearcases only. Standard gearcase models require a different service kit.

Why are 2 gearcase drain seals included?
Many gearcases use sealing washers at both the drain and vent screws, so replacing both helps ensure a proper seal after service.

How do I confirm compatibility?
Verify your engine serial number is 0R042475 or higher and confirm your outboard is equipped with a Command Thrust/Bigfoot gearcase before ordering.

• Engine Application
  • 9.9 HP Carb (209cc) - 0P325500-1R279944
  • 8 HP Carb (209cc) - 0P325500-1R279944