If running without oil injection, a 50:1 ratio is required, roughly one pint of 2 cycle oil, to six gallons of fuel.
87 octane oil mixture of 40:1
The dry weight of an 1990 model, 115 Mercury outboard is 326 lbs.
The plug gap for the 1990 model, 100 hp Mercury outboard is .040 in.
1990
The listed dry weight for a 1990 model, 75 hp Mercury outboard is 299 lbs.
A 35 hp Mercury outboard, serial number OC144498, would be a 1990 tear model.
An 8 hp Mercury outboard, serial number OC231325, would be a 1990 year model.
A 115 hp Mercury outboard, serial number OC238909, would be a 1990 year model.
1990-91.
The year, 1990
I believe it is 50 : 1 (16 oz. oil to 6 gallons gas)
A 1990 Model, 40 hp Mercury outboard, has a dry weight of 182 lbs.