Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 17Get this manual
Permanently Installed Fuel Tan ks Insert large, clean funnel with metal end filter in the tan k's fi ller open ing and pour pre-determined ratio of Formu la 50-0 oi and gasoline simultaneously into the fun nel as the tank is bei ng illedOperate new outboard motor at varied hrottle settingsnot to exceed 1 throttle (2500-3500 RPM) during he first hour or the first fifteen gallons of break-in fuelDuring he second hour operatio n, or the second 15 gallons of break-in fuel, operate the outboard at va ried throttle settings not to exceed 4500 RPM
2If fu ll hrottle operation is below the recommended range, the prope ller MUST BE changed to lower pi tch to prevent loss of performance and possible engine damage
3 For better accelerationsuch as is needed in water skiing, propping up to SOD RPM above the recommended range is advisedContinuous operation above he recommended max imum RPM, however, is not permissible4After in itial propeller installation, the following com mon cond it ions may requ ire that the propeller be changed to lower pitch: aWarmer weather and great humidity will cause an RPM lossbOperating in higher elevation causes an RPM losscOperating with damaged propeller or dirty boat bottom or gear housing causes an RPM lossdOperation with an increased load (additional passengers, equipment, pulling skiers, etc