Mercury - 300 Hour Maintenance Kit MerCruiser 5.0L & 5.7L MPI Alpha Series OEM Service Components 8M0147068. Overview. There's a certain peace that settles in when you turn the key and your MerCruiser 5.0L or 5.7L MPI fires up exactly the way it should. No hesitation, no odd sounds-just that familiar, steady rumble that tells you your boat is ready for another long run. The Mercury 8M0147068 300 Hour Maintenance Kit is built for that moment. It's designed for boaters who'd rather spend their wee