I use butter. no more than a a couple millimeters slice from a stick for 2 eggs. no stick. warm the pan to a low heat. cook eggs on lower heat (should be doing that anyway regardless of pan)

I can normally fry eggs in a cast iron in about a tsp (5 ml) of oil.

I also make scrambled eggs, but tend to use a tbsp (15ml) butter, but that is more for flavor and texture than to keep from sticking