I also use Gas Buddy to help find diesel fuel. One trick I've learned is going to Kroger food stores and using fuel points at their fuel centers. Not all of their fuel centers have diesel but the ones that do are marked on your Gas Buddy app. If you have one near you can usually save anywhere from .03c a gallon and if you have caught the store offering 4x fuel points and bought gift cards you can save even more. I put 35 gallons of diesel in ours for $3.64 total at one stop here in Nashville, TN.