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Mercury | 300 Hour Service Kit | 20/30 HP | 8M0120839

The Mercury 300 Hour Service Kit – 8M0120839 provides the essential maintenance components required to perform the recommended 300-hour service on Mercury 20 HP and 30 HP four-stroke outboards with serial numbers 0R106999 and above. This complete kit combines the critical oils, filters, cooling system components, ignition parts, and seals required to keep your engine operating reliably.

Routine service intervals help maintain proper lubrication, cooling efficiency, and overall engine performance. By replacing common wear items such as spark plugs, filters, thermostat components, and the water pump impeller, this kit helps extend engine life and maintain dependable performance on the water.

What’s Included in This Kit

• 2 x Quarts 25W-40 Synthetic Blend Engine Oil
• 1 x Quart Gear Lube
• 1 x Oil Filter
• 1 x Fuel Filter
• 1 x Oil Drain Seal
• 2 x Gearcase Drain Seals
• 1 x Thermostat
• 1 x Thermostat Gasket
• 3 x Spark Plugs
• 1 x Water Pump Impeller Kit
• 1 x Anode

Benefits of the 300 Hour Service

• Maintain engine lubrication with fresh 25W-40 synthetic blend oil.
• Protect the lower unit with new gear lube and drain seals.
• Ensure proper cooling performance with a new thermostat and water pump impeller.
• Improve ignition efficiency with fresh spark plugs.
• Reduce corrosion by replacing the sacrificial anode.

Engine Compatibility

• Mercury 20 HP Four-Stroke Outboards
• Mercury 30 HP Four-Stroke Outboards
• Serial Numbers 0R106999 and Above

Always verify your Mercury outboard serial number before ordering to ensure proper compatibility.

• Engine Application
  • 25 HP Carb SeaPro - 0R051710 and up
  • 25 HP EFI Jet 3 CYL - 0R165086-1R162636
  • 30 HP EFI 3 CYL - 0R106999-1R162636
  • 25 HP EFI 3 CYL - 0R106999-1R162636