Home Forum Ask A Member Gas to Oil Ratios

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  • #288916
    JohnRude
    Participant

      Canada Member

      After a hiatus from the outboard motor hobby to focus on old wooden boats I find myself back with motors. Somehow the number multiplied over the year. (My wife has the same problem with coat hangers!). I am learning to love small horse power. Mostly it’s because I can lift them. Near the bench are three 3 hp Johnson JWs. The 1960 and 1961 have fueling instructions printed on the front recommending 1/3 of a pint of oil to 1 gallon of gas (US). That’s 24:1. (J4J). The 1967 JW22-C states 1/6 of a pint of oil to 1 gallon of gas. That’s 50:1. (J6J).  What happened over those six years?

      Thanks to many at AOMCI I have several 5 1/2 and  7 1/2 Johnsons and Evinrudes (1955 through 1958) humming away. The recommended mix is 16:1. Confused?

      #288929
      The Boat House
      Participant

        The oil got better and has to continued to improve.
        Factory ratings changed over 50 years ago. Tubs

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        #288936
        JohnRude
        Participant

          Canada Member

          Thanks Tubs, I have that 1971 Service Notice. I will go forth with trepidation and use 24:1 for the early 60s and 40:1 for the 1967.

          I also note that they recommend “Leaded” gas for all.

          #288939
          labrador-guy
          Participant

            US Member - 2 Years

            Just a little note here about the gas.  Back in the fifty’s Kiekhaefer recommended using white gas, which is unleaded gas.  Don’t know why but Elmer (Carl) always liked to be different!  It does make spark plugs last longer!

            dale

            #288941
            crosbyman
            Participant

              Canada Member - 2 Years

              no more leaded gas….           on pre 60s  oldys  I use  25/1     1L oil /25L fuel   twc3   ad cd qd….

              up to you

              Joining AOMCI has priviledges 🙂

              #288944
              JohnRude
              Participant

                Canada Member

                I can learn new things. I’ll shake off that 16:1 urge for the mid to late fifties. But after so much work and so much help from the forum to get my 55 Evinrude 5.5 back to life…..well, I worry.

                #288947
                The Boat House
                Participant

                  Thanks Tubs, I have that 1971 Service Notice. I will go forth with trepidation and use 24:1 for the early 60s and 40:1 for the 1967.

                  I also note that they recommend “Leaded” gas for all.

                  Read the asterisk that applies to your model

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                  #288995
                  fleetwin
                  Participant

                    US Member - 2 Years

                    I can learn new things. I’ll shake off that 16:1 urge for the mid to late fifties. But after so much work and so much help from the forum to get my 55 Evinrude 5.5 back to life…..well, I worry.

                    OK, this perpetual discussion continues.

                    For sure, outboard oils have improved over the years, no doubt.  The question is has the oil quality improved enough to lube those plain rod bearings adequately at a lower ratio?   Perhaps on the 3hps.

                    But, on the 5.5s/7.5s, I don’t think so.  I would always stick with the original 16:1 recommendation.  The beauty of these old engines is that when in proper tune, they hardly smoke, even at 16:1.  That rod set up is definitely the weak link to otherwise bullet proof engines.

                    What about the argument that “OMC even recommended lighter ratios on these engines using the newer oils”.   I’m thinking most of those recommendations came from short time OMC staff/engineering/sales folks that had little or no experience with the 5.5/7.5 models.  Keep in mind that it was probably the same type of OMC staff the promoted the 100:1 mix in the 80s, and we all know how that went.

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                    #289003
                    frankr
                    Participant

                      US Member

                      Back in “The Day”, I asked an Evinrude Engineer, face-to-face, about what changed to make older motors ok with 50-1.  He said “sometimes, they just found out that their motors didn’t need as much oil as they thought they did”.

                      But is today’s oil better?  Hey, back then you could go to your local gas station and buy used drain oil in glass bottles with a metal pour spout.  It was sold as re-refined oil or something like that.

                      1970’s era was the start of the outboard horsepower race.  They were making 140hp motors in similar size and weight as the old Fat-Fifty.   Terrible timing, leaded gas was also being phased out.  And high performance/high compression motors were busting pistons from pre-ignition and detonation caused by low octane gas.  The lead was needed for the octane rating in those cases.

                      Cars too, I owned two high compression cars, a 110hp Corvair and a Pontiac Bonneville. The lead was needed for the octane. I had the timing set so far back in the Corvair that it couldn’t get out of its own tracks.  But it still pinged even while going downhill.  Both cars were sold because I couldn’t get gas for them.

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                      #289015
                      The Boat House
                      Participant

                        The models that are known to be prone to repeated connecting rod failure indicates a flaw in the design. Just adding excessive amounts oil can’t resolve that. I would suggest you use the best oil available and limit the time you run the motor wide open, if at all.
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