Although I am a committed Shell gasoline guy ( the 5% rebate on the gas card has been a godsend lately and my car seems to love it) I will glady use Mobil in a pinch. (I have had very good milage and performance with Mobil, and I believe that it has a good detergent package). We do have a few Exxon stations around here, and oftentimes the price is quite competitive. Is Exxon gasoline "different" in any significant respect from Mobil? (The parent company is Exxon/Mobil , so I figure that it must be the same fuel.) Anyone know the answer?