Originally Posted by DrRay
While what you say is absolutely true, there is a recent problem with this generalization. Most pump gasoline in NA is now supplemented with up to 10% ethanol at low octane numbers. Higher octane gas typically does not blend with ethanol.
Yes, you get better mileage with higher octane gas, but it's not because of the octane rating, it's because of the lack of ethanol.
Cheap ethanol blended gas is a false economy.
I disagree. There is no benefit of using higher octane if your car cannot advance timing to take advantage of the slower, more controlled burn
. I am curious to your data that supports the claim that the same different octanes located at the same station have different ethanol levels. I don't think I've heard of this before.
Our Armada doesn't get better mileage on 93 and, in fact, actually gets worse mileage for the fuel not getting burned completely. No power increase, nothing. But there is a mod called 2 degree (self explanatory) that will help get better fuel economy and power off of 89 over 87.
Mathematically, based on my un-scientific tests, I will save a total of $70-ish over the course of an entire year (15k mi) by using 93. While that is nothing to write home about, I will ultimately pay less and have better performance to boot.