2001 Mercury Mariner 50-60HP Factory Service Manual, Page 31Get this manual
MAINTENANCE
CHECKING LUBRICANT LEVEL AND FILLING GEAR CASE
Gear Case Lubricant Capacity 22.5 fl oz (655 ml) 1Place outboard in vertical operating position2Remove the front vent plug and rear vent plug3Place lubricant tube into the fill hole and add lubricant until it appears at the front vent holeAt this time install the front vent plug and sealing washer4Continue adding lubricant until it appears at the rear vent hole5Stop adding lubricantInstall the rear vent plug and sealing washer before removing lubricant tube6Remove lubricant tube and reinstall cleaned filldrain plug and sealing washer
aFront Vent PlugRear Vent PlugFront Vent HoleRear Vent HoleFillDrain Plug and Sealing Washer
Submerged Outboard