PREMIUM FUEL

  • moler02
    Iowa, Knoxville
    Posts: 525
    October 23, 2009 at 6:16 pm #1264689

    Information only, not trying to upset anyone. I have been told by a couple outboard techs, that running higher than recommended octane gas would only shorten plug life by sooting them up faster. That is for what it’s worth only.

    complex12
    Madison Wi
    Posts: 63
    October 23, 2009 at 7:18 pm #811148

    Quote:

    Information only, not trying to upset anyone. I have been told by a couple outboard techs, that running higher than recommended octane gas would only shorten plug life by sooting them up faster. That is for what it’s worth only.

    Might be true, might not be. I don’t think my ’74 Merc cares a whole lot.

    The problem is that premium fuel is almost always the only way to avoid ethanol… which the Merc does care about.

    igotone
    Posts: 1746
    October 23, 2009 at 7:43 pm #811154

    Quote:

    Information only, not trying to upset anyone. I have been told by a couple outboard techs, that running higher than recommended octane gas would only shorten plug life by sooting them up faster. That is for what it’s worth only.

    I run a 95 mariner 115hp

    And I would have to disagree with the sooting issue

    I try to run the Ultimate fuel from BP and I see less soot build-up inside the prop hub

    just my 2cents

    pockets
    Golden Valley, MN
    Posts: 145
    October 23, 2009 at 7:56 pm #811157

    Not all “Premium” fuel is ethonal free. They have to mark the pumps stating that it is. Otherwise, it has the same amount as the other grades.

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    October 23, 2009 at 8:04 pm #811160

    May or may not be true. Depends a lot on 2-stroke or 4-stroke. In any case, you should ask the follow up question to that blanket statment.

    “What plug should I use to account for the premium gas I plan to use” Noting the fact that premium will burn slightly cooler than 87 oct.

    One last comment – If it aint broke, don’t fix it!

    Good luck!

    -J.

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    October 23, 2009 at 8:12 pm #811162

    Quote:

    Not all “Premium” fuel is ethonal free. They have to mark the pumps stating that it is. Otherwise, it has the same amount as the other grades.

    True! I start running premium non-oxy this time of year. (Alway sells as premium 91 or better) I’m a firm believer that non-oxy will store better that the 10% ethenol fuel.

    -J.

    David Anderson
    Dayton, MN
    Posts: 520
    October 23, 2009 at 8:17 pm #811164

    This is possible. Higher octane simply raises the flash point of the fuel making it burn slower. If your outboard (or anything else) is designed to run on regular, the timing has been set to optimize based on the compression and regular gas. Running premium would possibly cause the fuel to not burn completely because there is no way to differentiate the two fuels when it comes to timing. In a car a knock sensor can tell the timing to [censored], but not to advance because of higher octane. My snowmobile can run on both however if you run premium the key has to be switched to a different position that changes the timing to utilize the fuel better.

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    October 23, 2009 at 8:25 pm #811170

    Quote:

    Running premium would possibly cause the fuel to not burn completely because there is no way to differentiate the two fuels when it comes to timing.

    David, I agree with your comments. I’m pretty sure you can overcome the difference with a hotter burning plug to account for the premium fuel in an outboard. Especially in a 2-stroke application.

    -J.

    complex12
    Madison Wi
    Posts: 63
    October 23, 2009 at 9:18 pm #811186

    Quote:

    Not all “Premium” fuel is ethonal free. They have to mark the pumps stating that it is. Otherwise, it has the same amount as the other grades.

    I realize that. What I meant was, with the exception of the few stations around that have no EtOH in ANY of their grades, the low-octane fuels(i.e. regular and super grades) will always have EtOH content.

    Grouse_Dog
    The Shores of Lake Harriet
    Posts: 2043
    October 23, 2009 at 11:47 pm #811231

    BURN NON OX 100% of time!

    walleyejoe
    Litchfield, MN
    Posts: 463
    October 24, 2009 at 1:36 am #811256

    I would rather pay more for the non-oxy than pay $120 percarburator on my merc and I have a 4cyl with 4 carbs. Its worth it and I know mine runs better on 91oct than 87 because I have tried it and I actually get 3 more mph with the 91 and the same load. Hands down non-oxy

    jon_wbl
    Posts: 289
    October 24, 2009 at 3:49 am #811288

    2 years using non ethanol premium. Not a single carb issue. Hot or cold no problems with my yamaha 4 stroke. Minnesota Street Rod Association (MSRA) website has a listing of stations that sell non oxygenated premium. Those guys don’t want to run the junk either.

    85lund
    Menomonie, WI
    Posts: 2317
    October 24, 2009 at 10:36 pm #811357

    I have an 1985 Merc 115 Tower of Power. I bought the boat 2 years ago from the original owner. He always used premium non ethanol gas and suggested I do the same. We had a lengthy conversation, possibly a training course for me, on things I should do to keep the boat, motor and trailer in tip top shape. This is the first big boat I have owned and I am so grateful for him for being willing to share all of his knowledge with me. I could see that he was happy the boat was going to someone who would baby it just like he had for the last 20 years.

    Another big thanks to the IDO members and staff who are so willing to help those of us learning the ropes. This site is a great wealth of knowledge and it shows.

    Thanks,

    Russ

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