The simple reason for running lower octane in my engine is - I have DA50-R which runs on 87 and that is what Desert Aircraft tell you to use in the instructions, and I also verified with them via phone - with this in mind - when I go to the field and I have both planes with me I prefer to have only one gas can, and since I can run 40:1 mix in both motors, 87 octane works for me. Do you know Pa, and what makes him an expert?