88 octane in the Chicago area as stated above is E15, meaning it contains 15% ethanol. You usually see it mostly at the discount chains, like Thronton. Usually runs a few pennies per gallon cheaper than Regular 87. Does it hurt? Probably not on most newer vehicles built within the past 20+ years, but I would avoid it like the plague in any outdoor lawn/snow equipment. While I wouldn't personally make a steady diet of it, I have used it once or twice in our 4 cyl. Jeep when it was the only thing available. As also mentioned, you'll probably get slightly less energy/mpg, negating any pennies saved per gal. Because it is harsher on lines, rubber, pumps, it may shorten their life, hence the warning to NEVER use in outdoor equipment.