Newer oils in old outboards

[rezeen]

What is a good rule of thumb for using newer 50:1 oils in antique outboards? Most of these older engines called for a 16:1 30wt motor oil mixture. We've been recommending a 25:1 "break in" mixture with modern 2-cycle oils to be on the safe side, but I've been wondering if this is too conservative. Any comments/recomendations on full synthetic oils would also be helpful.

 

[tmcalavy]

Re: Newer oils in old outboards

Anything older than 65 should get 24:1 at least, or 16:1 as their instructions say. This is because they have busings, not bearings. If you don't want to burn it up stick with the original instructions if they are there. If not, 16:1 is pretty safe bet, regardless of the oil used.

 

[Oil Man]

Re: Newer oils in old outboards

ebw,<br /><br />Most of these engines are not used very hard -- they aren't pulling skiers or making long full throttle runs. You could probably get by with a little leaner mixture. There isn't much harm in runing richer mixtures unless plug fouling is a concern. That is where a good synthetic will really help. They burn much cleaner, thus reducing plug deposits and reducing ring problems.<br /><br />Dave

 

[JB]

Re: Newer oils in old outboards

I mostly agree with Tim. Find out the "book" recommendations and use that ratio, but use modern, TCW-3 oil.<br /><br />New oils are better than old oils, but should not be expected to work with incorrect mix ratio.<br /><br />Good luck.

 

[cpasseno03]

Re: Newer oils in old outboards

This sounds a bit rich to me, perhaps im wrong? I have a 1965 johnson 40hp that I have been running 50-1 through. When I first got the thing I ran it quite rich what with it sitting for a few years I'm sure. After checking with the local Johnson man he assured me 50-1 was right, you have got me wondering now....<br />Craig

 

[Bear]

Re: Newer oils in old outboards

Craig Passeno,<br />I have used 50:1 in my '65 Johnson 6 hp for almost 10 years now. No problems. (For what it's worth )<br /><br /> fuelil ratio <br /> Proper 50 to 1 Fuel to Oil Ratio

 

[clanton]

Re: Newer oils in old outboards

Check parts book for engine, if crankshaft is roller, needle bearings, and wrist pin is needle bearing, 50-1 should be ok. The 1965 Johnson 3 and 5 1/2 HP is not an all roller/needle bearing engine. The 1965 Johnson 40 HP is an all roller, needle bearing engine.

 

[JB]

Re: Newer oils in old outboards

1965 was the first year that OMC recommended 50:1. It is probably safe in any ball and needle bearing engine (including wrist pins).<br /><br />EDIT: I was writing this when Clanton posted. I like his answer better.

 

[Bear]

Re: Newer oils in old outboards

Clanton,<br />The last 5.5 hp Johnson made was 1964 model, CD-CDL-21.<br />I have a 6 hp 1965 model, CD-22. There was no 5.5 hp in 1965.

 

[clanton]

Re: Newer oils in old outboards

Bear you are right, the 1965 was a 5HP.

 

[BillP]

Re: Newer oils in old outboards

What years did OMC have the 100:1 ratio (non-vro)?

 

[clanton]

Re: Newer oils in old outboards

I do not know the year spread, but that was changed back to 50-1 by service letter from OMC. OMC also had a 6 gallon fuel tank that had a oil mixer in the tank for the small engines, they had a kit and paid warranty to convert these tanks back to 50-1.

 

[Forktail]

Re: Newer oils in old outboards

This goes back to about 1964....<br /><br /> http://www.goa-northcoastoil.com/tips/obmixing.html

 

[BillP]

Re: Newer oils in old outboards

Thanks guys, <br />FT,it was on the link you provided...85-89 =100:1.