Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 16Get this manual
Fuel Mixture and GasolineOil Recommendations and Engine Break-In Procedures Gasoline Recommendations
.il.CAUTION
Use of Improper gasollnes and or oils can cause serious damage to your outboard motorIMPORTANT: Always use fresh gasolineGasoline forms gum and varnish deposits, Bnd may cause trouble il held In tank tor too long
Oil Recommendations
CAUTION
The use of other than recommended gasoline and Quicksilver Cycle Outboard 011 or an acceptable 011 BIA TC-W may cause piston scoring, bearing failure or both DO NOT, under any circumstances, use multigrade or other highly detergent automobile oils or oils which contain metallic additivesIn an emergency, if Quicksilver 2-Cycle Outboard Oil is not available, substitute high quality 2-cycle oi that is intended for outboard use and meets BIA rating TC-W, shown on oil containerUse the oil manufacturer's recommended gasoline-oil mixture as shown on the lable, not to exceed 50:1
Any good grade regular leaded, premium (Super) unleaded (lead-free) gasoline, with minimum posted octane rating 10 86 (researc octane number 90) is satisfactory for use in these model outboard motorsWhile the use of the preceding grades of g8solines are acceptable, for optimum performance we recommend the use 01 premium (super) unleaded g8soline