FYI..Good Sam offers a discount on diesel fuel, which is great and I may have occasion to use it. Here in Central Texas Flying J is charging $2.75 for diesel...I pulled in to a Buc-ee's a few miles fu...
Google Maps displays fuel prices when you search gas stations also. I find gas buddies data to be incomplete at times, also true of GM. Sometimes FJ is price competitive, there are no universally true rules on fuel sourcing if you travel widely.