Correct gas/oil mix for 1955 Johnson seahorse 10

[Mike Anderson]

Hi all, a new member here with a question about the correct gas/oil mix for a 1955 Johnson Seahorse 10. I just bought a Larson Crestliner 14 foot boat and it came with a 1955 QD-16 Johnson Seahorse 10 horse motor. In the instruction manual it says to mix one-half pint of Mobiloil Outboard motor oil per gallon of gas. That figures out to a 16:1 ratio. Do you still use that ratio of 16:1 when mixing gas with today’s’ modern two stroke oil?

Thanks in advance!

[dave-bernard]

I always do. some say you can use less BUT oil is cheaper than parts.

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Mike Anderson

[bobw]

You should absolutely stay with 16:1.  As Dave noted, some folks use less oil but the connecting rod bushings need lots of lube.  And as Dave noted, oil is a lot cheaper than new parts.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

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Mike Anderson

[Mumbles]

The required mix is 24:1 but you have to read the manual carefully as it says one quart of oil to a full tank of gas, which is six US gallons.  That makes a 24:1 mix but further on the manual says ‘for ease of measurement’ to mix one half pint of oil with one gallon of gas, which is for smaller amounts. I’m assuming the company figured it was easier for the average Joe to measure out a half pint instead of one third of a pint of oil. This would allow for a bit of error on the users part to protect the motor in case in case they didn’t measure out enough oil.

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Mike Anderson

[crosbyman]

see comment    #257222 in the  post  below …… on the same issue  16 vs 24 /1

 

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• This reply was modified 2 years, 7 months ago by crosbyman.

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Mike Anderson

[joecb]

More oil is better than less!!! With the modern oils, concerns for fouling plugs is much less than in the old 30 W / 40W days.  For you motor, at least 24:1 … a little richer will not hurt a thing…. unless you are a mosquito.

Joe B

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Mike Anderson

[frankr]

Back in the olden days, outboard oil came in 1/2 pint cans, as well as quart cans.  Convenience factor was obvious.

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Mike Anderson

[Steve A W]

I figure we’re trying to preserve history and old motors,

so don’t skimp on oil.

Member of the MOB chapter.
I live in Northwest Indiana

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Mike Anderson

[fleetwin]

I would stick with the 16:1 on this engine, even though I believe the factory recommendation is 24:1.  Like others have said, the heavier mix will help preserve the plain wrist pin bearings, which is a weak spot on these engines.

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Mike Anderson

[Mike Anderson]

Thanks for all the replies. The 16:1 ratio is what I will run in it. I don’t have any history on this motor so we will see just how well it runs.

• This reply was modified 2 years, 7 months ago by Mike Anderson.

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