what Octane and why????

[lake_time_2]

I have read that you should not run higher octane gas in 2 stroke outboards .. I have a 90hp mariner 1989, what grade gas should I run and why?<br />Thanks as always … Dave

 

[snapperbait]

Re: what Octane and why????

87 to 89 octane... The higher the octane rating, the harder it is for low compression motors to burn the high octane fuel completely...

 

[lake_time_2]

Re: what Octane and why????

So this would case carbon build up?

 

[snapperbait]

Re: what Octane and why????

Yes, It could under certain circumstances....

 

[Bear]

Re: what Octane and why????

I can't answer the what question or the why question.<br />But check this out: <br /> Topic: Octane <br />

 

[JB]

Re: what Octane and why????

Howdy, lake-time-2.<br /><br />Use what the book recommends, because that is what the engine was designed to use. Most recommend 87 octane unleaded. Some suggest higher octanes.<br /><br />Good luck.

 

[lake_time_2]

Re: what Octane and why????

thanks for all the info guys.. the problem is i think i am about the 20th owner of this old girl and so i dont have the book. Anyone got a 1989 mercury/mariner 90hp that they can look up what is recomended?.. Thanks as always... Dave

 

[snapperbait]

Re: what Octane and why????

From Clymer Mercury service manual.. 1972-1989...<br /><br /> "All Mercury inline outboards require the use of a minimum posted pump octane rating of 86 for lead free gasoline."..