What is the oil to fuel ratio I must use for my boat?

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We recommend a 25:1 or 20:1 gas to oil ratio.  This is 5 or 6 ounces of 100% synthetic oil  (we recommend Amsoil Saber Pro or Honda HP2) added to 1 gallon of LOW octane gas (87 to 89).  This is ideal for most applications.  Do NOT use high octane or race fuel (this can harm the engine).  Once you choose the mix ratio, do not vary from it.  During engine break-in (typically 1.5 to 2 gallons of fuel through the engine), you should vary your running speed and avoid running full-throttle.  Always be careful to not over-rev the engine.  We recommend Bonzi Break-in Oil(one bottle will break-in 2 engines) for faster break-in with top performance.

You will have a break-in period with your engine.  Usually it takes about a gallon to a gallon and a half for you to achieve top performance.`

Information on octane measurement methods – Click here 
(.pdf format)

Octane Measurement Methods

  • Research Octane Number (RON)
    The most common type of octane rating worldwide is the Research Octane Number (RON).
    RON is determined by running the fuel in a test engine with a variable compression ratio under
    controlled conditions, and comparing the results with those for mixtures of iso-octane and nheptane.
  • Motor Octane Number (MON)
    There is another type of octane rating, called Motor Octane Number (MON), or the aviation
    lean octane rating, which is a better measure of how the fuel behaves when under load as it is
    done at 900 rpm instead of the 600 rpm of the RON. MON testing uses a similar test engine to
    that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and
    variable ignition timing to further stress the fuel’s knock resistance. Depending on the
    composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than
    the RON. Normally, fuel specifications require both a minimum RON and a minimum MON.
  • Anti-Knock Index (AKI)
    In most countries, including all of those of Australia and Europe the “headline” octane rating
    shown on the pump is the RON, but in Canada, the United States and some other countries, the
    headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI). It
    may also sometimes be called the Road Octane Number (RdON), Pump Octane Number (PON),
    or (R+M)/2.
  • Difference between RON and AKI
    Because of the 8 to 10 point difference noted above, the octane rating shown in the United
    States is 4 to 5 points lower than the rating shown elsewhere in the world for the same fuel.
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