Correct Fuel to run 86 Merc 115 hp

[Coke1]

"Does anyone know for sure, wh

"Does anyone know for sure, what the correct fuel is, to be using in an 86 Merc 115hp? Originally, the motor was designed to take leaded fuel at about 94 or maybe 96 octane. (Mixed with oil at 50:1) Now it obviusly has to run unleaded. But should I be using regular unleaded at 92 octane, or mid range at 95 octane, or high performance octane of 98 rating? And should I be mixing lead additive with it, or not? I know of similar motors detonating pistons recently, and the talk has been that it is due to the new unleaded fuel replacing the traditional leaded fuel. Does anyone know for sure??? Thanks!"

 

[dave gearl]

i have a 1986 mariner the manu

i have a 1986 mariner the manual says to use 87 octane unleaded so i would guess to mix oil at 50 to 1 and use reg pump gas if you get any pinging then step up a grade hope this helps and happy boating

 

[scallywag]

"Just a side note concerning o

"Just a side note concerning older model two cycle outboard motors burning "modern" gas. The fact that lead is no longer added to gasoline is not the only concern for older 2 strokes. The fact that ethanol is now more prevalent in fuel and increasing in percentage is a major scurge. E-10 gasoline(that is 10 percent ethanol) wich is the target in Ontario for 2010 is the max for newer outboards.Older outboards not calibrated for this risk hard starting and corrosion to shorter range and outright engine failure. The reason? Ethanol flushes sludge from fuel lines etc. settles to the bottom of tanks along with condensate (water)
plugging filters.Ethanol tends to clean lubriacating oil off cylinder walls, crank bearings etc. causing wear and overheating. Also with premix fueled engines when the engine is started it starts on ethanol and water NO OIL PREMIX Keep your tanks clean. What fuel is in your tank? E-5? E-7? With quotes from Outdoor Canada Mag."