4-6hp FourStroke 300 Hour Maintenance Kit
Complete Your Purchase
Mercury Marine 4-6hp FourStroke 300 Hour Maintenance Kit
The Mercury Marine 8M0120836 300 Hour Maintenance Kit is a genuine OEM package containing all the components needed to perform a complete 300-hour service on Mercury 4, 5, and 6 horsepower FourStroke outboard engines (serial numbers 0R411838 and above). By bundling every required service part into one convenient box, this kit removes the guesswork and hassle of sourcing individual components, allowing boaters and technicians to complete scheduled maintenance efficiently using common shop tools.
Produced to Mercury Marine's stringent original equipment manufacturer specifications, each component is engineered for a precise fit and reliable performance in your Mercury or Mariner outboard. Following the recommended 300-hour service interval — as outlined in your owner's manual — helps protect your engine investment, extend engine life, and maintain strong, consistent performance on the water. The kit is suitable for use in both saltwater and freshwater environments and works with tiller and remote-steer configurations.
Compatible vessel types include dinghies, sailboat auxiliaries, jon boats, tenders, small inflatables, compact skiffs, and lightweight fishing boats. The included impeller and seals restore proper cooling system flow, the filters support clean and steady fuel delivery, and the thermostat and spark plug contribute to easy starting and smooth operation under load.
Key Features
- Complete selection of required 300-hour service replacement items in one box — no need to order separate parts
- Includes fuel filter, oil drain seal, two gearcase drain seals, thermostat, thermostat gaskets, spark plug, water pump impeller kit, and unit anode
- Genuine Mercury Marine OEM part — not aftermarket — manufactured to exact OEM specifications
- Designed for Mercury 4 HP, 5 HP, and 6 HP FourStroke outboards, serial numbers 0R411838 and above
- Restores cooling flow, clean fuel delivery, and proper ignition performance
- Periodic maintenance is easy using common shop tools; follow owner's manual for recommended service intervals
- Produced to maximize the performance of Mercury and Mariner outboards
- Helps maintain warranty compliance and engine resale value
