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Mercury | 300 Hour Service Kit | 15/20 HP | 8M0120838

The Mercury 300 Hour Service Kit – 8M0120838 provides the essential maintenance components required to properly service Mercury 15 HP and 20 HP four-stroke outboards with serial numbers 0R235949 through 0R833819. This complete kit simplifies scheduled maintenance by bundling the required oils, filters, cooling system components, ignition parts, and seals needed for the 300-hour service interval.

Regular maintenance ensures reliable engine performance, improved fuel efficiency, and long-term durability. By replacing worn service components such as spark plugs, filters, thermostat, and the water pump impeller, this kit helps keep your Mercury outboard running smoothly and operating at the proper temperature while protecting critical internal engine and gearcase components.

What’s Included in This Kit

• 2 x Quarts 10W-30 Synthetic Blend Engine Oil
• 1 x Quart Gear Lube
• 1 x Oil Filter
• 1 x Fuel Filter
• 1 x Oil Drain Seal
• 3 x Gearcase Drain Seals
• 1 x Thermostat
• 1 x Thermostat Gasket
• 2 x Spark Plugs
• 1 x Water Pump Impeller Kit
• 1 x Anode

Why Perform the 300 Hour Service?

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

Engine Compatibility

• Mercury 15 HP Four-Stroke Outboards
• Mercury 20 HP Four-Stroke Outboards
• Serial Numbers 0R235949 – 0R833819

Always confirm your Mercury outboard serial number before ordering to ensure proper fitment.

• Engine Application
  • 15 HP Carb 2 CYL - 0R235949-0R833819
  • 15 HP Carb 2 CYL JCI - 0R558208-0R833819
  • 20 HP Carb 2 CYL - 0R235168-0R833819
  • 10 HP Carb 2 CYL - 0R575531-0R833819