The engines that I am referring to have plain bushings on the large end of the rods….None of the engines you mentioned have this set up. I am not concerned about the plain crankcase bushings as far as lubrication is concerned. I’m pretty sure the old Bigtwins had an original mixing recommendation of 24:1, so that is fine. The 72 25hp had a recommendation of 50:1, so that is fine.
Have oils improved since the 1950s, sure. In the end, these are your outboards to lubricate anyway you wish.
