All DEF is standardized and is exact same chemical composition regardless of brand. I usually buy it where it’s more convenient as the difference in price between house brands and premium brands is not worth it for me to drive somewhere just to buy DEF. Often DEF is sold at commercial truck stations right next to diesel. This is a good and economical way just to top off DEF if you stop by to refill your van. When topping off DEF, always keep handy plastic gloves and paper towel as splashed DEF will stain your engine compartment if not cleaned right away. Having DEF funnel is good for those truck stop refills. Otherwise DEF by a gallon is sold in special containers that come with built in spout and plastic hose. DEF funnel