Unless one literally tests every tank... there is no way to really know what CRAP is going into your tank. Torrie says always run NAME BRAND FUEL... I run Costco, Murphy, Pilot, etc... and I believe that the cheapest price for 93 OR 91 is the best place to buy, due to volume sold.
You are quite right Bob and on top of that, who knows what crap is in the underground tanks...between water, dirt, and God knows what else, it's kind of amazing there isn't more fuel related issues.
