ORIGINAL: RoswellGrey
Aside from the (I believe) 100 octane "racing fuel" a buddy of mine once got, about all I've ever seen is 87, 89 and 91. Often, stations in San Antonio only have 87 and 91, with no middle grade.
Personally, although it's an SE, I've been using 89 octane (I try to use only Shell, as I consider it the best on sale here) in the Challenger. When my salesman and I were talking, I asked him about what fuel to use and he told me that although the car would run fine on regular, when Dodge does its fuel-economy ratings, they use 89 octane. I figure if it's good enough for Dodge, it's good enough for me.
That's strange. Do they have anything else like diesel, racing fuel, or (and I seriously doubt this in Texas but I'll ask anyways) E-85 in the place of offering mid-grade?
From a person who has owned a couple 3.5L powered Chrysler products in the last six years, you will want to use 89 octane. That is what they recommend and it will run much smoother on it.
I use either Phillips 66, QT, Gateway F/S (local brand, that several mechanics recommend above national brands), or MFA Oil (a more local brand that landed on the top tier gas list). The advantage of Gateway F/S and MFA Oil is they generally have mid-grade for the same price or lower than regular due to the 10% Ethanol content which the national name brands in this area contains in all grades regardless; therefore, it makes you ask yourself why wouldn't you go with this option if the quality is the same and the price is better. My favorite brand though is actually Texaco; however, around seven years ago, they all disappeared in this area and switched over to many other brands, especially Shell.