Back in “The Day”, I asked an Evinrude Engineer, face-to-face, about what changed to make older motors ok with 50-1. He said “sometimes, they just found out that their motors didn’t need as much oil as they thought they did”.
But is today’s oil better? Hey, back then you could go to your local gas station and buy used drain oil in glass bottles with a metal pour spout. It was sold as re-refined oil or something like that.
1970’s era was the start of the outboard horsepower race. They were making 140hp motors in similar size and weight as the old Fat-Fifty. Terrible timing, leaded gas was also being phased out. And high performance/high compression motors were busting pistons from pre-ignition and detonation caused by low octane gas. The lead was needed for the octane rating in those cases.
Cars too, I owned two high compression cars, a 110hp Corvair and a Pontiac Bonneville. The lead was needed for the octane. I had the timing set so far back in the Corvair that it couldn’t get out of its own tracks. But it still pinged even while going downhill. Both cars were sold because I couldn’t get gas for them.
