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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 10W-30 synthetic blend four-stroke oil, this bundle covers the most common milestone service items—engine oil and sealing, gearcase service parts, fuel filtration, cooling components, ignition parts, and corrosion protection—so you can keep your small outboard starting easily and running reliably.

Serial number range: 0R042475 & Above

What’s Included in This Kit

• 1 x 10W-30 Synthetic Blend 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 items in one kit.
• Cooling system refresh: Thermostat and impeller service helps maintain proper water flow and stable operating temperature.
• Fuel-side protection: Fresh fuel filtration helps keep debris and contamination away from critical components.
• Corrosion defense: Includes an anode to help reduce galvanic corrosion in marine environments.

Service Notes

• Designed for Mercury 8/9.9 HP models with Command Thrust/Bigfoot gearcases only.
• 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 use a different kit.

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

How do I confirm this kit matches my outboard?
Verify your engine serial number is 0R042475 and above and that your outboard is equipped with a Command Thrust/Bigfoot gearcase.

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