I usually use the Murphey's station at our local Walmarts. Never had any problems, fuel prices usually at least 20 cents cheaper than at the convenience stores. Lots of people filling up so they should keep fresh fuel.

 

Never purchased diesel from our local Sam's Club, but get gas there every time I'm in town and need to fill up. Lot's of businesses fill up there so I would have no problem buying it if needed.