1/2 a pint of oil per gallon of gasoline means you will be creating a ratio of 1 part oil to 16 parts gasoline. You want to use oil that says TC-W3 on it. (meaning Two Cycle, Water cooled, version 3) This means it satisfies the most up to date requirements for a two stroke water cooled engine like yours. (Yes TC-W3 oil was not a thing in the 1950s but it is better for your engine than what they had then because it should create less carbon deposits inside the engine and should stay mixed better with the gas, and probably more reasons I don’t remember involving lubrication too).
I use this to figure out how much oil to put in the amount of gas I buy:
https://www.premixcalculator.com/
What you want to do it bring a clean and 100% empty gas can to the gas station. Don’t bring the gas tank mounted on your motor, as pure oil or pure gas may stay unmixed in the fuel line and you don’t want that. Once you have a gas can (there are soooo many vintage ones in good shape for cheap on Facebook Marketplace), bring it to as gas station that sells ethanol-free gas.
Ethanol is added to most gas nowadays to “reduce” emissions (but fossil fuels are consummed to produce it), however it is not suitable for older engines as rubber parts that were not designed for ethanol compatability don’t last as long (get brittle I think) and ethanol can cause corrosion. So look for ethanol-free gas. It may be called recreational or marine gas but just because gas may have one of those labels does not mean it will be ethanol-free. It’s up to you to check. However, there are people who use ethanol gas in older engines with a minumum of trouble. Ethanol-free is simply my reccomendation based on lots of online research. I have not fuelled up any of my outboards or small engines with ethanol gas, and I do not plan to.
Once you find your gas station, have your gas can, your oil, something to measure your oil in, and have figured out how much fuel you want, measure half of the total amount of required oil and pour it in the gas can. Next, put half of the amount of gas you want in the gas can. Use the guage of the fuel pump for that. Next, put in the 2nd half of the total amount of oil you need. Now put in the 2nd half of the gas you need. Now seal the gas can and shake. The shaking and specific order of gas and oil addition both help the fuel and oil mix together so your engine is thoroughly lubricated.
If you notice you accidentally put a little too much gas in, add a touch more oil. Sadly, there have been many two stroke engine failures because of insufficient oil so a little more oil is safer for your outboard than a little less. I.e. Your engine will be fine at 15 to 1. In fact, I have run a 16 to 1 engine at around 14.5 to 1. (There was some disagreement between my oil bottle and oil measuring device). Modern two stroke oils are thinner than older ones, according to what I’ve read anyway. I haven’t tested. This means you shouldn’t have to worry about the fuel mix being too thick to reach the internal componants if you put in a touch of extra oil as the fuel mixture would likely have been thicker in the 1950s anyway.
2 final notes:
1 – Air cooled engines run hotter than water cooled engines, so air cooled two stroke oil (for leaf blowers, weed whackers and the like) is not the best choice for your engine. TC-W3 oil is designed for the operating tempurature of a water cooled engine like yours. I think that using the correct oil will aid in heat dissipation, but you should fact check me on that.
2 – Don’t forget about lubricating the lower unit gears. Yours could either take grease or oil. I don’t know which, but would think likely grease. Do not use NLGI #2 grease (commonly found thickness) as it’s too thick. Many outboard collectord have had success with NLGI #0 greases like John Deere Corn Head grease in lower units requiring grease. If yours takes oil, there are plenty of marine outboard gearcase oils to choose from.
I hope this helps you.
Have fun getting it running!!!😁
