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Mercury | 300 Hour Service Kit | 8M0097857

Hit the 300 hour milestone with confidence using a complete service kit for Mercury 75–115 HP 1.7L four-stroke outboards. This kit is built around 25W-40 four-stroke oil and combines the core oil-change and gearcase items with the additional wear parts commonly addressed at the 300 hour interval—cooling components, ignition parts, belt service, and corrosion protection. It is a straightforward way to refresh critical systems, reduce downtime, and keep your outboard running strong for the next season of use.

Serial number range: 1B366823 – 2B094995

What’s Included in This Kit

• 1x 25W-40 Four Stroke Oil (Gallon)
• 2x 25W-40 Four Stroke Oil (Quart)
• 1x Gear Lube (Quart)
• 1x Oil Filter
• 2x Fuel Filters
• 1x Oil Drain Seal
• 2x Gearcase Drain Seals
• 1x Thermostat Kit
• 1x Belt
• 4x Spark Plugs
• 1x Water Impeller Repair Kit
• 1x Power Trim Anode
• 1x Lower Unit Anode

Why This 300 Hour Service Kit Matters

• Milestone service coverage: Goes beyond oil and gear lube to address cooling, ignition, and belt wear items.
• Cooling system refresh: Thermostat and impeller components help support stable operating temperatures.
• Fuel-side protection: Fresh fuel filters help reduce debris before it reaches sensitive EFI components.
• Corrosion defense: Includes trim and lower unit anodes to help reduce galvanic corrosion.

FAQ

Why are there 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.

Why replace spark plugs at 300 hours?
Plugs can wear and foul over time. Replacing them helps support clean combustion, smoother idle, and dependable starting.

What do the anodes protect?
Anodes help protect key submerged metal components by sacrificing themselves to reduce galvanic corrosion.

How do I confirm this kit matches my engine?
Verify your outboard falls within the listed serial number range before ordering.

• Engine Application
  • 75 HP EFI - 1B366823 – 2B094995
  • 80 HP EFI - 1B366823 – 2B094995
  • 90 HP EFI - 1B366823 – 2B094995
  • 100 HP EFI -1B366823 – 2B094995
  • 115 HP EFI - 1B366823 – 2B094995