Yamaha F100B F100C Outboards Factory Service Manual, Page 56Get this manual
Periodic checks and adjustments
Initial
50 hours (3 months) 100 hours (6 months)
500 hours (every 30 months) 1000 hours (every years) 200 hours (1 year)
Remarks
Lower unit Gear oil ImpellerWoodruff key Oil seals Drive shaft Propeller General AnodesTrim tab Battery Wiring and connectors Nuts and bolts(5) Lubrication points Rubber seals Bearings Exhaust system deterioration