Old outboard

[Early Riser]

I just picked up a 1953 Johnson 5.5. The gas in the external tank is at least 2 - 3 years old with stabil. I probably wouldn't have run the motor with this gas but the people I bought it from were already running it to see if it would start. Sure enough it runs beautifully. Now I want to run some fresh gas through it. What do you guys recommend? Anyone know of preferred oils and oil mixtures for these old engines? The tank says "add one half pint of SAE 30 motor oil per gallon of gas." Thanks for any advice you can give.

[Great Dane]

I had an old 5.5 Johson and they did call for a lot of oil, but the new outboard oils are so much better they will foul your spark plugs at that level. I gradually weaned mine down to 40 to 1 and the more I did, the better it ran. I just sold it last month after 45 years and it still ran great.

[New Yankee]

The tank calls for 16:1, but I've never heard of anyone running more than 24:1 which is recommended for OMC motors up to 1964. I don't disagree with Great Dane, the TWC-3 oils availible today are much more effective than the old 30W used back in the motors hay day.

That being said, I'd suggest 24-1. Run non-oxygenated gas if it's availible, avoid ethanol if possible. If it were me, I'd probably run some seafoam for a couple of tanks to decarb a bit.

Those old motors sure bring back memories don't they?

Perhaps Airjer,ST or Val will chime in if I'm off base.

[eurolarva]

Is this motor air cooled or water cooled. If it is air cooled you should not use a TCW3. Air cooled motors run hotter then water cooled. If it is water cooled then TCW3 is the oil of choice.

[Early Riser]

Thank you for the insights and ideas guys. I do have a couple more questions:

I found some pure premium gas, added about 1/4 can of seafoam and went with valvoline premium SAE 30 at 24:1. It seemed to run well although I had to adjust the mixture to slightly more lean at higher RPMs.

What would you guys have to say about the right amount of seafoam to add to 4 gallons of gas for the carb? Is 1/4 can too much or not enought to do much?

I am not too sure yet if it is air or water cooled. Water seems to sputter out of the exhause port in back, but there is no water pump that sprays out in a nice straight stream.

Can I start with the newer style 2 cycle oil by adding a 24:1 or 40:1 blend to the current SAE30 mixture, or should I wait until the current tank is used up?

[Valv]

I believe Johnsons were only water cooled. I any case it will not have the "telltale" stream like newer models, it will discharge from rear and exhaust. Carefully put your hand on head, cylinders, etc to feel if it gets too hot.

[Surface Tension]

I'd use any premix 2 cycle outboard oil. What ratio? If I were to believe modern oils to be superior in lubrication, is that enough to lean out the mix and to what extent. There isn't any data or chart to go by. The outboard has made it over 50 years running on a SAE 30 16:1 mix. Do you think we'll see any modern (2007) outboards that have to comply with EPA standards around 50 years from now? I doubt it.

If it were mine I'd go as much as 24:1 with "modern" 2 cycle oil. I'd also never put oxygenated gas in the tank of any outboard with an old fuel system. BTW those old Rudes and Johnsons could be converted from pressure tank to fuel pump.

The Seafoam would be a good idea. Use it as directed on the can. A shock treatment to get rid of the years of carbon build up would be a good idea too. One can to one gallon of mixed gas.

[Fishin4Life]

I run my 59 Johnson at 24:1, no problems and there isn't excessive amounts of smoke either... The guy I bought it from is very familiar with Johnson motors and said not to run any leaner than 24:1 or you could risk damage of the motor.