For those that like 100-1 ratios, here's three example engines that changed the way a lot of things were done. As for specifics, suffice to say that they ran more than 15 minutes or so at a time, and all of them should have lasted a lot longer than they did. Generally low time engines as these things go. The oil was a top of the line synthetic designed and specified by the manufacturer to be usable at 100-1 ratios. The piston that looks wet around the edges had fuel pumping through it due to a windmilling propeller for quite a distance. The appearence of chipped edges is where carbon had broken free from the piston. Every engine had a partially stuck ring.
BTW, they all flew and sounded great, and there was very little oil residue on the aircraft after extended periods of operation. The plugs were checked and changed far more frequently than most people flying R/C would ever consider. All of them flew great right up to the point they quit running. Many, many more experienced the same issues with similar results. All those had stuck rings too.
Now I'm not going to try to tell anyone what they should or should not mix their gas and oil ratios at. But I won't run any of mine at 100-1 anything. I've got three twins and 5 singles and I don't need to buy any of them again. Now if I needed an engine for a new plane buying another engine is another story altogether
BTW, 50 to 70-1 synthetic mixes leave a little oil on the bottom, but a little clean up is cheap insurance. Anymore my personal outlook is that if I'm seeing some oil on the bottom I'm in the ballpark for a workable oil ratio.