I want to use it so that the cake comes out smoothly.
If you use aluminum foil, it's true that the cake won't stick to the pan, but it WILL stick to the foilYou will have to grease the foil just as much as the bare pan, it'll save on clean up time, howeverI'd skip the foil, as it might be more cumbersome than the effort's worthbutter/shortening the pan, and sprinkle with flour (white/yellow cake) or cocoa if you have it for chocolate cakeIf you do use the foil, it shouldn't mess up your cake, but may have an effect on baking time - watch you cake a bit more carefully.
