Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 219Get this manual
Gear Housing Lubrication (Filling) Instructions AWARNING
If gear housing is installed on engine, to avoid accidental starting, disconnect spark plug ignition wires before working near the propeller
6Replace upper lubricant vent screw and washer and contin ue filling until excess starts to flow out of lower lubricant vent screw hole7Replace lower lubricant vent screw and washer8Remove lubricant tube from fill hole; install fill screw and washer
ACAUTION
DO NOT use automotive grease In the gear housingUse only Quicksilver Super-Duly Lower Unit Lubri-