Cooking oil helps remove adhesive left behind by vinyl stickers because it works by breaking down the sticky residue. The oil penetrates the adhesive, softening it and making it easier to wipe away without damaging the underlying surface. The lubricating properties of the oil also reduce the friction between the adhesive and the surface, allowing for a smoother removal process. This method is gentle and effective, making it a popular choice for cleaning up sticky residues. Obviously, after smothering the surface with oil, you will have to then clean the oil up with some glass cleaner a few times.