If your going to decide to run 89 i suggest shell, might be different in your area, but down in vancouver 89 at shell is rated at 5%ethanol.

 

i accidentally ran 87 in my twin turbo setup not knowing that the shell only had regular. i was scared that i might run into issues with knocking and pinging but it seemed to be okay ran fine but got really bad fuel millage. No ecu reset or anything just started and drove

 

I've run my fx35 on low grade fuel with ethanol for over five years (85k miles) with no issues. This includes 20+ ski trips per year into the mountains with a fully loaded vehicle.

On a side note, when I changed out my sparkplugs at the recommended interval they were totally shot, but I'm not sure if this was because of the fuel...

 

Car will run fine with 87 octane, with a slight decreased in performance like another user noted. My dad 01 Acura tl ran on 87 since he bought it, now it has 130k miles.

 

Ok call me crazy but pure ethanol freezes at -173.2 degrees fahrenheit. Gas freezes at -104/-140 degrees. E85 is also 103-105 octane allowing for more timing and more boost to be run because it doesn't knock or pre-detonate like 91-93. So because of cold weather you'd want more ethanol and to hold knock back you'd want more octane. Gas with 10% ethanol won't freeze as easy and will be better for knock if you were to run 87-89. A 87 octane fuel with 10% ethanol will be better all around than 87 with 0% ethanol. The only bad thing about ethanol gas is gas mileage because ethanol burns a lot faster.

Knock isn't good!! Wonder why cars lose compression over time? A pistons ringlands are the weak point. Knock can micro crack them at that point. Add boost to a micro cracked ringland and guess what happens? Ever seen a WRX or STI motors ringlands? Guess what happened? Knock. We don't have boost so micro cracks aren't a big deal but not only will you kill performace for that tank but you'll be hurting it long term too. You guys running 87-89 for years, put your car on a dyno and run it then.

 

Also you have to remember altitude as one of the key factors in Octane the lower the altitude the higher the Octane needs to be.
In 99% of the cars you will not see a difference on 87 vs 91 at 6000 feet. And our car will be fine but not at sea level it needs 91 .
If you never go over 70 it will never matter.
Your computer will adjust since our cars are meant to think about the gas your using.
All gas is not equal only Tier 3 which is name brand like Shell, Chevron and Phillips 66 etc.

 

i read your original post fully. too bad you lack proper comprehesion skills and technical knowledge. just to let you know ethanol "is not" antifreeze.
antifreeze is "ethylene glycol". the internal combustion engine is not designed to run on ethylene glycol, it will definitely cause a misfire. ethanol is a grain alcohol and in this country its derived from corn. in addition not all gas stations carry ethanol blended gasoline. ethanol blended gasoline will give you slightly less mpg because it contains less energy as fuel source.