Oil/gas ratio? Evinrude 7.5

Geoff Pike

Geoff Pike

Active member
Is there a typical oil to gas fuel ratio for two-stroke outboards?
16:1 seems right to me but I cant figure out why. I aquired an older
Evinrude 7.5 but nothing came with it, not even from the previous owner.
Any help would be great.

Thanks
Geoff
 
50:1 (or 1/2 quart of oil to 6 gallons of fuel) is typical but I'm not a mechanic. I may be corrected.

Ed L.
 
The sad part is I am a mechanic, just not an outboard mechanic.....
I hate single cylinders and no camshafts..

Really Ed thanks for the quick reply, 16:1 sounded right but also seemed
really rich.

Geoff
 
It depends on how old your motor is. Like Lee said. My 67 3hp takes 24:1. Good luck. If you can, post your year and model # and we can figure it out.
 
We're running a late 60's or early 70's 9.5HP Evinrude and the mix is 24:1. You could try googling it and see what comes up. Typically older outboards run richer mixtures than do newer outboards. My 25 HP Evinrude is about ten years old and I'm running it in the 40 to 50:1 range.

Bill G.
 
I KNOW THAT IT SOUNDS CRAZY BUT I HAD A 1970'S EVINRUDE 15HP WHICH RAN 100/1. I WOULD CERTAINLY PUT MORE OIL THAN THAT IN IT, SOMETHING LIKE 50/1 AT LEAST. POINT IS, IT COULD BE ANYTHING.
 
The previous owner is correct. Older Evinrude FleeTwin outboard motors of the 50's vintage use 1/2 pint to the gallon mix (16:1). If your motor cover has a lid cover over the gas cap, look under this lid for the mix instructions for the correct ratio to use. If you do not have this, some of the information is as follows:

** LUBRICANT - Use a high grade oil of S A E 30 or 40 body such as MOBILOIL Outboard or comparable straight mineral oil.
** Mix 3/4 pint oil with each gallon of gasoline for first four hours then reduce to 1/2 pint per gallon.

Changing the ratio with a newer type oil would be a good question for a knowlegeable mechanic and would depend on the internal parts of this style motor.
 
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From what I have read, since the invention of TC3 Outboard oil, the old heavy mix's can be lightened up quite a bit. Post your question over on iboats.com in the proper forum and see what they say.
 
Run Amsoil Saber (ATO). If you normally use 50:1 with oil, it will be 100:1 with Saber synthetic with a lot less mess dripping from the prop. Saber is also suppose to be around 70% biodegradable so it is more green to the environment and you use less of it per tank. I have no complaints about using it, my motors run well with much less smoke and good performance.
 
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