Ya'll need to read up on where your gasoline comes from. Important things that you should know.
http://www.eia.doe.gov/neic/experts/contactexperts.htm
http://science.howstuffworks.com/gasoline.htm
I can tell you that when I cruise to Texas on Leave (9hour trip), I use 89 Octane w/o any problems. Matter of fact, till I added the Greddy Ultimate and got tuned, my car ran better on 89 as per 93 Octane. That's a TRD S/C running 9PSI. The Scion ECM will take care of you, as long as, it is not 95F+ and/or your hotrodding around.