Oil Mix for ’57 Merc Mark 25

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  • January 28, 2023 at 7:24 am #271923
    wabittle
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      Hello. I have a 1957 Mercury Mark 25 and I am wondering what the best oil mix is for this motor. I have been running it at 32 to 1 using Quicksilver oil and non-ethanol gas. I have a 1962 shop manual that states it can be operated at 50:1 using Quicksilver oil. What is the current accepted oil ratio given modern gas and oil? Thanks.

      January 28, 2023 at 9:17 am #271927
      fastjohn
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        US Member - 2 Years

        Even though you can run it at 50-1, I run all my Mercs at 40-1.  32-1 is a little rich but will not hurt it.

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        wabittle
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