Amen. Walmart. I was buying it from Home depot or autopart stores for around $12. Until I asked my wife to buy it in Walmart. She called me from the store and asked me if I want one for $12 or $6. I told her to buy one of each. Cheap one was in blue square tank and the one for $12 was in clear tank in paper box. Hose on the one for $12 bucks was dripping while I was pouring it in and cheap one did not. I know which one I will be buying from now.Walmart
Be careful at smaller stations. They could possibly have 2 problems.WM has plenty of inventory turnover not to worry about expired product.
I don't go to truck stops much, their fuel prices are much higher vs other smaller stations closer to where I live. (But their DEF is cheaper)