Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 21Get this manual
MAINTENANCE
Checking Lubricant Level and Refilling Gear case
1Place outboard in vertical operating position
2Remove vent plug (a)3Place lubricant tube (b) into the fill hole and add lubricant until it appears at the vent hole (e)4Stop adding lubricantInstall the vent plug and sealing washer (a) before removing the lubricant tube 5Remove lubricant tube and reinstall cleaned filldrain plug and sealing washer (d)
Storage Preparations
Fuel System