>I might grease a metal hinge

No you've missed the point. I know that what you are saying is fine. We obviously use the word grease in different ways. I wouldn't associate the word grease with food, although we might talk about cleaning a greasy plate caused by the fat from the food. When I hear the word grease the first thing that would spring to mind would be removing thick black axle grease from an engine part, the next thing would be something like Vaseline or the grease that used to be used to slick back hair (as in the film). Hence my reaction to the idea of a hamburger frying in grease (even though I saw you use the Phrase "its own").