Want to know more about how your engine is breaking-in or wearing? Curious about whether or not your oil is doing its job? Want to be ahead of problems that may develop? PartsVu has partnered with Blackstone Laboratories and we are now offering professional oil analysis kits. Results are typically received in a few days via email. Shop now.

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

The Mercury 300 Hour Service Kit – 8M0120839 provides the essential maintenance components required to properly service Mercury 20 HP and 30 HP four-stroke outboards with serial numbers 0R106999 and above. This comprehensive maintenance kit includes the critical oils, filters, cooling system components, ignition parts, and seals needed to complete the recommended 300-hour service interval.

Performing routine maintenance helps maintain dependable performance, protect internal engine components, and ensure proper cooling and lubrication. This kit simplifies the service process by bundling the most commonly replaced components so you can efficiently complete scheduled maintenance and keep your Mercury outboard operating at peak performance.

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
• 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

Why Perform the 300 Hour Service?

• Maintain engine lubrication with fresh 10W-30 synthetic blend oil.
• Protect the gearcase with new gear lube and drain seals.
• Ensure proper cooling with a new thermostat and water pump impeller.
• Improve ignition performance 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 engine serial number before ordering to ensure compatibility with your Mercury outboard.

• Engine Application
  • 25 HP EFI Jet 3 CYL - 0R0165086-1R162636
  • 30 HP EFI 3 CYL - 0R106999-1R162636
  • 25 HP EFI 3 CYL - 0R106999-1R162636
  • 25 HP Carb SeaPro - 0R051710 and up