Like LG says, it depends on the engine…. Using 24:1 on an engine with bronze bushings on the rods could result in a disaster, regardless of today’s improved oils, stick with the original 16:1 recommendation. Older engines with needle bearings would probably be “OK” with less than the 24:1 mix, but it is not worth the “gamble”. The beauty of the old OMCs is that when they are in good shape, and tuned properly, they don’t smoke much once started and warmed up, even with the 16:1 mix.
Tell us which 1950s OMCs you are running… Many of today’s younger techs have had little or no experience with the older outboards, they are just spewing the hype from the oil companies and manufacturers.
