fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

[tallcar]

wondering what the correct fuel/oil ratio for these two clasics would be?

 

[sloopy]

Re: fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

50:1 or 25:1 depending on conditions

 

[almost retired again]

Re: fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

Hi Tallcar,<br />OMC once put out that you could run any engine that they made on a 50/1 mix if the engine was first de-carbonized. I personally have run several older engines on a 50/1 mix with no problems. However I think that most folks on this board will tell you that you need a much richer mixture. The Mercury I think, always had needle bearings, so I believe that a 50/1 ratio will work there also. All that I have to back me up on the above is a set of notes taken at an OMC school in 1972. I wish that I could find the service bulletin that they put out, but over the years a lot has gotten lost, or not updated properly.<br />Hope that this helps

 

[tallcar]

Re: fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

Thanks sloopy, i currently run 50:1 in the Johnson, and that things just putters at about 1.5 m/p/h runs great, the Merc is still under construction( only have fire to one cylinder, have to swap coils to check other)

 

[JB]

Re: fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

Howdy, Tallcar.<br /><br />While many folk do get away with using 50:1 in older engines you should take into account that the reasons that modern engines use 50:1 are not because the oil has improved (which it has) but because the engine technology has improved.<br /><br />The Johnson Service Manual for your '56 Johnny states that it should use 24:1 mix. If it were mine it would be following the manufacturer's specs.<br /><br />I don't have factory specs on your Merc, but because of it's age I would use 24:1 there until I got Factory specs.<br /><br />Good luck.

 

[tallcar]

Re: fuel/oil mix for '56 Johnson 5.5 and '56 Merc 25E

Thanks to all on the gas mixture, I will immediately change the ratio..