Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 499Get this manual
Maintenance Instructions Lubrication and maintenance inspection is owner's responsibility and must be periormed at intervals specified, following:
Normal ServiceEvery 50 hrsof operation or 60 days (whichever comes first) Severe ServiceEvery 25 hrsof operation or 30 days (whichever comes first)