When Johnson specified SAE#40 for their outboards
it was all that was available at the time. The development
of TC-W oil was to have better product designed to be
mixed with gas for better lubrication and longer life.
As early as 1971 they were recommending TC-W oil
at 50 to 1 to be used it the earlier motors and not to
use crankcase oil except as a last resort. The
development of TC-W oil has continued so we now
have TC-W3. How people can sit behind a computer,
with a smart phone in their pocket in their pocket,
in their air condition home and then look to a manual
that is 60, 70, or 80+ years old as the best source for
the care as far as lubricants is something I cant
understand. For those of you who rely on that decades
old data let me try to bring you up to the 70’s anyway.

Tubs/Westwind,

I hear what you guys are saying, but is it really a good idea to run a 1936/37 Johnson 300 at 50:1, regardless of the oil you are using? I don’t see motors of this vintage listed in the chart above. I’m a little hesitant to try this. Maybe I’m just being paranoid, but just because you’re paranoid doesn’t mean they’re not really out to get you.

For the umpteenth time they don’t make parts anymore for these eighty year old motors so why try and save a quarter by seeing how little oil they can survive on? Going lean as possible on the oil is nothing more than playing Russian Roulette with them and sooner or later the motor will lose. The only reason the antique motors are still here with us today to play with is because their previous owners did read and follow the manufacturers recommendations for the fuel/oil mix. As we all know, factory recommended lean mixtures in the mid eighties put OMC on the brink of bankruptcy with warranty repairs. Just because they made the product doesn’t mean their oil ratios are designed for the motors longevity but probably more for it to give a certain number of service hours before being worn out and needing replacement hopefully by another new OMC product. In the sixties, the engineers probably realised the old low horsepower motors from the thirties weren’t wearing out fast enough and by reducing the amount of life giving oil in the fuel mix, they would wear out faster making a replacement necessary. Corporate greed and profit comes into play here. Now that I got that off my chest, I’m off my soap box and it’s someone elses turn.

As a reminder, the club’s motto, which is at the top of this page, says ‘Dedicated to the Preservation and Restoration of Antique Outboards’ and the easiest way to help preserve an antique outboard motor is by feeding it the oil it needs for survival.

Back to the original question, the Johnson 300 uses 1/2 pint of oil per gallon, or 16:1 fuel/oil mix. Not 24:1, not 50:1 or 100:1, but 16:1.