Fuel mix for ‘65 Evinrude 3hp

[biologicole]

I have a 1965 Evinrude 3hp Lightwin that I’ve been working on. My question is about the fuel mixture. On the cowling it says 50:1 but during the re-build process I’ve seen many comments recommending higher oil mixtures such as 25:1 and 20:1 and even 16:1. The reason given for the higher oil concentration fuel mixture‘s are all pretty consistent in saying that Evinrude was a bit premature in recommending the 50:1 ratio and time has shown that the internal components of these engines actually need more lubrication than 50:1. I would like to know what everyone here’s opinion and experience is with this. Thank You

 

[Crosbyman]

never had issues at 50/1 on 50/1 engines mostly 1960's and up engines

if you are worried run 40/1 with quality oils

no sense is spewing more oil in the lakes by over oiling

 

[Sea Rider]

Yes, besides fouling plug and more carbon build up on powerhead internals at slow idle/fast idle speed for long time periods. Will be Ok with 50:1 ratio. Just buy a good 2 strokes oil brand TCW-3 rated.

Happy Boating

 

[oldboat1]

Your call, of course, but I would run it with the 24:1 ratio that was recommended through ’63. Use of better TWC3 oil will give cleaner burning over 30w oil that was originally used, but will not replace the lubrication provided with a richer ratio. Use J4J plugs if you can find them, otherwise J4C.

If the spirit moves, you might run 16:1 during break-in (ratio that was recommended for regular use in period 7 1/2 motors).

 

[Chinewalker]

+1 on the fatter mix. If it were my motor, I'd run it at 24:1 as the '65 3hp isn't appreciably different from the 1950s model, in that it has plain bearings throughout. It really would be happier, long term, with more oil in the mix. The 1950s models called for 16:1, so 24:1 is my concession to improved oil quality on that particular design.

 

[racerone]

It will run fine at 50:1 but it will last a few more years at 24:1-----If it is the only motor you have / can afford run at 24:1

 

[boobie]

I'd run it on 24:1 due to the bearing structure in the motor.

 

[jimmbo]

1964 was the year OMC switched to 50:1, for the entire line.

 

[boobie]

That was an advertising ploy. I was there.

 

[racerone]

Board room decision to try and maintain market share.-----Nothing scientific about going to half the oil.

 

[Bonaventure]

If the motor is mostly running at idle, (like for trolling), 50 to 1 will be OK. Generally 2 strokes need more oil at high speed. Idling with 24 to 1 will cause the plugs to foul more quickly. Also, the motor needs to have a residue of oil in the crankcase to prevent corrosion during winter lay-up, so more oil during the last run of the season is not a bad idea.

If you are running more at high speed, then a 24 to 1 may be prudent.

I have never heard of problems from the early days of 50 to 1, but I don't know everything.

 

[jimmbo]

Board room decision to try and maintain market share.-----Nothing scientific about going to half the oil.

What evidence, proof, or documentation do you have to support that opinion?

 

[biologicole]

Thanks for all the replies. Your help is greatly appreciated.