Octane isn’t about gas mileage. It’s about compression. Lower octane gas is prone to auto-ignition at lower compression ratios. Running lower octane gas in an engine designed for higher risks catastrophic engine damage, as ignition can happen before the piston has reached peak compression.
Reality is modern engines adjust timings to make up for lower than expected octane, because they have to deal with other situations that trigger it (e.g. elevation).
But running an engine designed to take advantage of a higher octane at lower octane will have a fuel economy hit. But appears to be a single digit percents difference while reducing unit fuel cost by over 15% where I am.
Correct, but the manner in which many do this is reactive (i.e. piezoelectric knock-detectors), not proactive.
I put max octane in all the cars I own. I don't see a reason to play games with something like this.
I am not a long haul trucker. I put maybe 100 miles on my vehicles per month.
The cost of fuel is not relevant to me.
Of what’s commercially available, that would be E85. I hope you’re not putting that into your E10 max vehicle.
But if you’re still under warranty and your engine blows up, it suggests a problem with the manufacturing itself. Exceptions could be if you put in E85 that’s not recommended as it has much lower energy and the engine needs to make a ton of adjustments for that which might be out of range.