I have a 2007 150 Mercury Optimax. I have been using 87 octain that has 10% ethanol. I use Stabil engine treatment for ethanol gas at every fill up. My question is, should I use a higher octain with out ethanol? Have been hearing bad stories about all makes of motors blowing up because of to much ethanol.. Thanks for the help.. 
Getting off of the ethanol is always a good thing. Anything synthetic ie rubber or plastic will deterorate when coming in contact with ethanol. Ethanol does not allow for water to mix with gasoline however the stabil you are using helps to prevent that. Recently I put up a post about the difference between Stabil Sea Foam and Startron after I submit this post I will try to find it and include a link.
That was easy. Here you go.
Well I recently went thru this thought process, my 07 200 OPTI I used 87 with 10% after reading that they are designed to use, I used the Quikleen and Stabilizer with out an issue for neither my kicker and Opti. I got my 010 200 Opti and the installing dealer pushed me to use Non Oxy fuel, well I revisited the article about Merc and ethenol and decided to switch back to 87 w 10% eth., the article I read said that 92 non ox burns cooler, which promotes plug fouling and decreased performance. Now if I ran an older engine that was not desighned for Ox fuel like my Evinrude 6hp, lawn mower etc….. Non Ox fuel for sure, those run and start better on non ox fuel
All I use for any of my motors other than the car is the Kwik Trip Premium…..
No ethenol…90oc…add a dash of Seafoam and I’m good to go. 
All the 92 oct at the Kwik Trips where I am have 10% ethonal in it. There is only one station in Chetek that has the 92 oct with no ethonal……..at least there was last year. Will find out today as I need gas when I get to the lake.
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Well I recently went thru this thought process, my 07 200 OPTI I used 87 with 10% after reading that they are designed to use, I used the Quikleen and Stabilizer with out an issue for neither my kicker and Opti. I got my 010 200 Opti and the installing dealer pushed me to use Non Oxy fuel, well I revisited the article about Merc and ethenol and decided to switch back to 87 w 10% eth., the article I read said that 92 non ox burns cooler, which promotes plug fouling and decreased performance. Now if I ran an older engine that was not desighned for Ox fuel like my Evinrude 6hp, lawn mower etc….. Non Ox fuel for sure, those run and start better on non ox fuel
this…. I’m more concerned about carbon, myself.
I have allways run the 10% ethenal and have never experienced any fuel issues with my Opti. I do keep Seafoam in my tank, hardly ever at the recomended dose usually add a can every other tank, I fill when half tank or less, my tank is 40 gallons.
Mercury desighned it to run on 10% ethenal.
100% non ox fuel in everything .
Kurt you are correct in what you say. The motors are made to run 87 and ethanol. All the gas will carbon up a motor and one point or another. It is a good idea to run a fuel conditioner. I would run ring free with the 87 during the summer. When it got closer to putting away for the winter I would switch to 92 non ethanol gas for storage.
Always add star-tron fuel enzymes, the best stuff on the market. It is made by starbright.I ran it in my 225 opti it never ran better.
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