1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 11Get this manual
General Maintenance Conduct periodic, systematic inspection to uncover and correct failure before it can cause injury, inconvenience or mechanical damage
EVERY 100 HOURS OF USE OR ONCE SEASON
1Inspect spark plugs2Check and adjust valve clearance, if necessary(Section Part 8) 3Drain and replace gear case lubricant(This Section) 4Change engine oil and replace the oil filterThe oil should be changed more often when the engine is operated under adverse conditions such as extended trolling(This Section) 5Lubricate splines on the drive shaft(Section 6) 6Inspect timing belt(Section Part 8) 7Clean fuel tank pick up filterEVERY 300 HOURS OF USE OR THREE YEARS
INSPECTION AND MAINTENANCE SCHEDULE
AFTER FIRST 20 HOURS OF USE
1Check fuel line filter for contaminants(Section 3) 2Inspect spark plugs3Check steering system for binding or loose components4Drain and replace gear case lubricant(This Section)5Check that lanyard stop switch stops the engine6Remote control modelsCheck control cable adjustments7Remote Control ModelsVisually check steering link rod fasteners for proper tightness(Section Part A)