Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 8Get this manual
Oil Recommendations ACAUTION
The use of other than recommended gasoline and Quicksilver 2-Cycle Outboard Oil or an acceptable oil NMMA or TC-W 11''' may cause piston scoring, bearing failure or bothDO NOT under any circumstances, use multi-grade or other highly detergent automobile oils or oils which contain metallic additivesIn an emergency, if Quicksilver2-Cycle Outboard Oil is not available, substitute high quality 2-cycle oil that is intended for outboard use and meets NMMA rating TC-W II TIl shown on oil containerUse the oil manufacturer's recommended gasoline-oil mixture as shown on the label, not to exceed 50:1
Mixing Instructions
AWARNING
Observe fire prevention rules, particularly NO SMOKINGMix fuel outdoors or in well ventilated locationIMPORTANT: Always use fresh gasolineGasoline which is kept in tank too long will form gum and varnish deposits which cause troubleMix fuel directly into remote tankPour small, equal amounts of gasoline and oil into tank Mix thoroughly, then add remaining oil and gasolineMix againKeep fuel clean and mix each batch of fuel exactly the same way to avoid carburetion problemsIMPORTANT: Use recommended amount of 2-cycle oilToo much or too little oil can cause performance problems, as well as serious engine damage