1965 3HP Lightwin Fuel - Oil Mix

[Underblog]

Just picked up a 3HP Lightwin (1965) in the Twin Cities.

From what I can tell, the manual specifies 50:1. Conventional wisdom on the non-repair board appears to converge on 24:1, since the 3HP ran the plain bushings longer than the larger motors. I am reading here on this board that many run 16:1 on their Lightwins.

Did they make a substantial change to the bearings between 1956 and 1965 that allowed them to use so much less oil?

 

[boobie]

Re: 1965 3HP Lightwin Fuel - Oil Mix

IMHO I'd use the 16:1. It may smoke a little and you may foul a pug, but you know you have plently of lube on that old of a mtr.

 

[TN-25]

Re: 1965 3HP Lightwin Fuel - Oil Mix

My opinion is that the biggest change between those years you listed was the change in oil when OMC started offering the new TCW 2-stroke oil over the old straight 30 weight automotive oil. OMC introduced a much better suited oil specifically for water cooled outboard use. It mixed better and stayed mixed without stratification, for one. The oil was introduced for 1964, coincidentally the same year OMC cut the official mix ratios from 24:1 to 50:1 (after break-in). OMC didn't revamp every motor for 1964 but they changed the oil recommendation with the new specialized oil. That is my conclusion.

The reality is that some of the bigger motors like the V4s & the 40 twins were ready for leaner oil mixtures before officially being sold with that claim.

For your 1965 Evinrude 3, officially it was supposedly safe to run at 50:1. Many people have gotten away with that, but also many have not. I would say that with the modern TC-W 3 lube you would be very safe at 24:1. 16:1 is pretty oil rich, and really I would run it at 16:1 if the only thing available was automotive straight 30 (can you even find that stuff anymore?). What you have heard about the plain bushings vs. roller bearings is true. The old 3s are great motors though, and one of my favorites.

 

[JB]

Re: 1965 3HP Lightwin Fuel - Oil Mix

You will be fine with 24:1, underblog, as you have been advised in your other thread. Duplicating threads is bad forum manners.

Please read and respect our rules. Thanks for your cooperation.

 

[SeaKaye12]

Re: 1965 3HP Lightwin Fuel - Oil Mix

Realistically too....it would depend on how you would typically run your motor. If you think you're going to run WOT for hours on end...that would be a good reason not to skimp on the oil. Trolling; you could probably get away with a lot less. The manufacturers recommendations had to be based on a variety of factors....and ensuring longevity under extreme operating conditions had to be a prime one.

For me; it would be what I call "the worry factor". If I ventured away from 16:1...I would be listening in fear for every odd sound. Unless of course; I passed out from the fumes

Chuck

 

[1946Zephyr]

Re: 1965 3HP Lightwin Fuel - Oil Mix

Yea, I would go with the 16:1 mix rule myself. The 3hp was built from 1952 and called for 16:1 the day they were introduced. Truthfully, this motor was the same design, all the way up untill 1978, with the exception of the top crank journal. I happen to own a 1955, 1957 and a 1965 3hp, plus a 1970 4hp and I think they're great little motors.
24:1 is okay I think, if you run at lower rpm's, but a motor that runs more at WOT, I would go with the 16:1 A richer mix may foul a plug sooner, but it'll only help prolong the life of a 47 year old motor. A J8C would be a good plug to use, if you run the richer fuel mix, to help it run better with less fouling issues. I know some would say a J8C is too hot, but my HD-20 Johnson was designed to take a J8C and it hasn't harmed it.