Whataburger's own ordering app publishes per-item ingredients, and they show a soybean-oil "Bun Oil" brushed on every bun, toast and egg, plus soybean oil and high fructose corn syrup baked into every bun. 40 of 41 food items name a seed oil and all 41 carry an additive, though the beef patty is just 100% ground beef.
Whataburger does not publish an ingredient guide, but their own ordering app exposes a full ingredient statement for every item, and it is not flattering. There is a component literally called Bun Oil - "liquid and hydrogenated soybean oil, soy lecithin, natural & artificial flavor, beta-carotene (color), TBHQ and citric acid, dimethylpolysiloxane" - and it goes on the buns, the toast and the eggs. Every bun begins unbleached enriched flour, water, high fructose corn syrup, yeast, soybean oil. Whatasauce leads with soybean oil and high fructose corn syrup. Of the 41 distinct food items, 40 name a seed oil and all 41 carry an additive; the one without a seed oil is Fruit Chews, which has Red 40 and Blue 1 instead. The beef is a genuine bright spot - "USDA inspected 100% ground beef" - and the eggs are fresh shell eggs. The fries are soybean oil and are then fried again in an undisclosed "ZTF Whataburger liquid shortening".