2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 90Get this manual
Power trim and tilt unit Lower unit 4Place drain pan under the drain screwremove the drain screw, then the check screw to drain the oil
S62Y3550
Check the oil for metal, discoloration, and viscosityCheck the internal parts of the lower case if necessaryInsert the gear oil tube or gear oil pump into the drain hole and slowly fill the gear oil until oil flows out of the check hole and no air bubbles are visible