25-30hp FourStroke 300 Hour Maintenance Kit

Mercury Marine 25-30hp FourStroke 300 Hour Maintenance Kit

The Mercury Precision Parts 300 Hour Maintenance Kit 8M0120839 provides everything required to complete a full 300-hour scheduled service on compatible Mercury 25 HP and 30 HP FourStroke EFI outboards. Designed for engines with serial numbers 0R106999 and above (through 1R162636 where specified), this comprehensive kit bundles all critical replacement components into a single, convenient package — eliminating the need to order parts individually and simplifying the service process.

Compatible with the following Mercury applications: 25 HP EFI 3-cylinder FourStroke (serial number 0R106999 and up where specified); 25 HP EFI Jet 3-cylinder FourStroke (serial number 0R165086 and up where specified); 30 HP EFI 3-cylinder FourStroke (serial number 0R106999 and up where specified); and 25 HP Carb SeaPro (serial number 0R051710 and up where specified). Always verify your engine serial number and parts diagram before ordering to confirm fitment.

Performing scheduled maintenance at the 300-hour interval maintains engine lubrication, protects the gearcase, ensures proper cooling system function, improves ignition performance, and reduces corrosion through replacement of the sacrificial anode. Following the service schedule outlined in your owner's manual keeps your Mercury outboard operating at peak performance and protects your investment in your boating experience.

All components are produced by Mercury Marine to stringent original equipment manufacturer specifications, making this kit suitable for Mercury and Mariner outboards as well as MerCruiser sterndrive applications where noted. Service can be completed using common shop tools.

Key Features

• Complete selection of required 300-hour service replacement items in one box — no need to order separate parts
• Includes oil filter, fuel filter, oil drain seal, gearcase drain plug seal, thermostat and thermostat gaskets, three spark plugs, water pump impeller kit, and unit anode
• Also contains low-pressure and high-pressure fuel filters, power trim anode, lower unit anode, and belt (per detailed fitment sources)
• Compatible with Mercury 25 HP and 30 HP FourStroke EFI outboards, serial number 0R106999 and above
• Genuine Mercury Precision Parts — produced to OEM specifications for maximum performance
• Serviceable with common shop tools following owner's manual procedures
• Helps maintain engine lubrication, gearcase protection, cooling performance, and ignition reliability
• Reduces corrosion with sacrificial anode replacement