Johnson CD-10 Fuel/Oil Ratios

[RiverRunner53]

I've been reading the advice about using a 24:1 ratio in "older Johnsons" but I recently picked up a 1954 CD-10 5.5 HP and the decal on the engine cover (which is still easily readable) clearly states .5 pint of oil for every gal. of gas. Going on what I remember from my H.S. cooking class: 1 gal = 4 qts = 8 pints = 16 half-pints (no pun intended), which yields a ratio of ...(anybody?, anybody?, class?) ...16:1. Is there a third fuel/oil ratio out there for some Johnsons that is not being discussed, or have my math skills "gone south" on me? This engine looks hardly used, so an answer saying using a 24:1 ratio is OK 'cause the engine is worn and slack is not going to really fly with me. On the other hand I fully expect a 16:1 ratio would cause the engine to smoke like an old oil-fired locomotive. Also important to note that I currently reside in "The People's Republic of California" so an excessively smoky two-stroke outboard will make me about as popular as a leper! Anybody want to weigh in on this? Thanks!

 

[cougar1985]

Re: Johnson CD-10 Fuel/Oil Ratios

running my new 1956 30hp jonny at 24:1. good thing about smokey is maybe the commies wont be able to see you to catch you.lol.

 

[Joe Reeves]

Re: Johnson CD-10 Fuel/Oil Ratios

Regardless of what any decal on that engine might state, the proper fuel/oil mixture is 24/1..... 1 quart of 50/1 TCW-III oil to 6 gallons of gasoline. A octane rating of 87 will be fine.

 

[F_R]

Re: Johnson CD-10 Fuel/Oil Ratios

16:1 is correct. It can survive on 24:1 if everything else is A-1. Best advice is run 16:1 and use 100% Synthetic TC-W3 outboard oil. That will smoke less and the oil slick is supposed to be bio-degradeable. Yeah, I know, try explaining that to the "man".

Let's face it, that is not a clean-running motor.

 

[tashasdaddy]

Re: Johnson CD-10 Fuel/Oil Ratios

there was a change in bearing in the 50's early ones were 16:1 later years 24:1, your math is correct. and using 16:1 tcw3 oil is recommended, synthetics smoke less. they originally ran on 30 wt non detergent oil.. that really smokes.

typing at the same time.

 

[JB]

Re: Johnson CD-10 Fuel/Oil Ratios

The 16:1 ratio was assuming that you were using SAE30 automotive oil. If you still want to use 1954 SAE30 oil then use 16:1.

If you want to use NMMA TC-W3 oil, then do what OMC and BRP tell you: Use 24:1.

Oh, by the way, even if you don't believe OMC and BRP you can take what Joe Reeves tells you about any JohnnyRude to the bank.

 

[RiverRunner53]

Re: Johnson CD-10 Fuel/Oil Ratios

Appreciate the answers from all concerned. Collective wisdom really seemed to come through in this case. I'll go with the 24:1 (even though I was tempted to go with the constant "smoke screen" theory of operation) using a synthetic TC-W3 (which is what I had planned to use in the first place). Thanks!