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Moisture in higher octane fuel?

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  • Moisture in higher octane fuel?

    I was chatting with a patient today about cars (not a new thing for me) and when rehashing the fuel/carb issues in Vancouver, he said something that I found intriguing.....

    According to his friend who is a Rover mechanic in Bellevue, use midgrade fuel in a British car because higher octane fuel holds more moisture!

    Is he making something up, or could it be just this simple? I did a quick search online but wanted to ask you all about your thoughts on this idea.


  • #2
    Hi Elise,
    I am glad to see you both made it through the Northern Adventure!

    I have many opinions, especially on fuel. Most aren't worth reading; but, read on if you wish.
    The theory I'd heard recently is that the Oxygenated fuels component that makes them "oxygenated" is a form of alchohol which likes to naturally "bond" with the moisture in the air.
    Now, of course, many will quickly post up saying no way man......

    But, the argument used by some for / against oxy fuels is sometimes leading to the amount of energy the fuel ( alchohol or other components in the fuel ) has. I've heard that octane is sometimes changed based on the oxy part.

    I don't know about that. What I do know is that owning and operating many german cars with F.I., during the 80's and 90's I began to see significant runability problems related to fuel and was told the same thing, use mid grade as the products / components creating the higher octane rating were actually creating the problems I was seeing in the several Bosch FI systems. Whether this was directly related to the oxy fuels component, I'm not sure. But since the mechanics were top notch, I listened to them. And, Mid grade didn't exhibit the problems that "super" did.

    Then, there is always the Top Tier gas discussion. Many automakers are now jumping on the Shell, Texaco, and Chevron bandwagon of market differentiation. ( Once you oxy any of them, who knows? )

    Now, to the point you started on ( Mini ). I know that my 998 runs better and gets better mpg on NON oxy fuel. So, as often as possible, I check the website:

    and buy my fuel there. Of course, Your mileage may vary.

    One obvious side comment that you both found out is that our old cars often have things ( water, dirt, etc ) hanging out at the bottom of our old cars tanks. Some of the "dewatering" products you can put in your gas tank are simply a form of alchohol or ethanol. ( Kind of makes you wish the gas tanks were clear so we could let them sit and settle out, then see that separation.)

    My fingers are cramping up, so it must be time to stop typing. Whew. Thanks for reading. ( I stand ready with nomex suit for the many opinions, attitudes, hearsay, and perhaps even malarkey to follow! )

    Best regards,
    All Together Now..... Everybody.......


    • #3
      Thanks for the great feedback Mark!! I really appreciate you taking the time and I found your input quite interesting!

      I was hoping someone would write something about this and not just have it float into the abyss of non-replies on the SAMOA forum!


      • #4
        Mark, very, very interesting reply to Elise's post.. Thanks for it and that link - good to know where one can actually get 'good' gas...