I look for fuel stations that advertise only 1 price. Indiana is so bizzar with prices between commercial vehicles and privately owned vehicles, it's crazy. So, I always look for a "normal" gas station that sells "car diesel". When traveling, avoid any and all places that have multiple prices ... even with credit card vs cash. When traveling through Illinois a few weeks ago, I even bypassed one station that had multiple blends of diesel on their pump... Talk about "What the ****!?" I had no clue and went on. 1/2 mile up the road was a normal station with a normal "car diesel" type pump and no multiple pricing...
That's just me. Others may do it different.