Thanks for this. I will start with the 91 octane on next fill. Not a fan of E-10, but use the 87 octane with that blend. And I have seen an ever-so-slight amount of “soot” at the pipes.
We do have E-0 in 87, 89, & 91 octanes also available in many of our local stations. Restricted mainly to “Top Tier,” refineries, I believe it is called? But once you cross that ethanol blend to tread into the non-ethanol party, the per gallon prices escalate. And, radically. So, bottom line for me is, “should I,” or “should I not?” I have found in my other vehicles as I fill with the higher priced upper octanes, I seem to benefit in the MPG categories. Kind of a trade-off.