Cooking: why I prefer butter (or margarine) to oil

Self-tutoring about pan frying: the tutor reflects.

When cooking in a frying pan, I use butter (or margarine), even if the recipe calls for oil. My reason: oil can heat up without giving any sign, whereas butter (or margarine) gives several indications that it’s getting hot: it melts, then starts to bubble and sizzle, and so on.