A lot of spray oil products contain lecithin, dimethyl silicone (anti-foaming), and either a propane or butane propellant. Over time, the lecithin builds up on the surface of the pan even if you clean it after each use. Trying to scrub it off is futile (experience talking), and also is damaging to the non-stick surface. Some manufacturers say that the sprays burn at a lower temperature which can damage the non-stick coating. My personal go to is shortening because it easily adheres to the non-stick finish, releases smoothly, and cleans up easily with no build up over time.