Mercury - 300 Hour Maintenance Kit L6 Verado Series OEM Components 8M0149428. Overview. If you've spent enough time behind the helm of a Verado, you know that nothing feels quite like the smooth push of an in-line six as it settles into its rhythm. And when you rely on your engine for long runs, heavy-duty schedules, or week-after-week usage, staying ahead on maintenance isn't optional-it's the heartbeat of your confidence on the water. The Mercury 8M0149428 Select L6 Verado 300 Hour Maintenance