Mercury 115 2 Stroke- how much 2 stroke oil will it use

[Prophammer]

I'm thinking about buying a 2007 boat with a 115 Merc 2stroke, or repowering the one I have with a 90 Mercury 2stroke. The 75, 90, & 115 were all the same engine turned up differently, right ? How much 2 stroke oil should I expect to use per 20 gallons of gas for the 115, and what about the 90hp? Thanks in advance for your answers!

 

[Quad82]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

Not sure what year motor you have. But I run 16 oz of oil to 6 gallons of gas (50:1) in my 1978 Merc 115.

 

[Faztbullet]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

The 75, 90, & 115 were all the same engine turned up differently, right ?

No ...the 75/80/90 are 3 cylinders and the 115/125 are 4 cylinders. It being oil injection the usage varies due to throttle setting as at idle its 80:1 ratio and at WOT it 50:1 ratio.

 

[Prophammer]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

My mind is cloudy because if been upside down in my bilge all day, so if I had a 50 gallon tank i would put in 1 gallon of oil right?

 

[Faztbullet]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

Only if the oil injection has been bypassed ...then yes as 128 oz is 1 gallon

 

[Prophammer]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

Thanks, My next question then, how bad on gas is a 115 2stroke pushing a 1200 lb boat, an how bad on gas is a 90 2 stroke pushing a 1000 lb boat?

 

[redjmp]

Re: Mercury 115 2 Stroke- how much 2 stroke oil will it use

My '86 inline 6 115 gets 5 mpg @3050rpm turning a 19p cupped ss prop on an 800lb 15 footer...
Drops to 3 mpg at wot