I don't eat axle grease, so wouldn't recognise the taste, but after the war, my mother, a farmer's daughter, used to take the cream off the extra milk ration she had for us small childrn and churn it into butter in a large sweet jar, so that we didn't need to use margarine.
i'd definitely prefer to eat a natural food than something from a chem lab.
When the first low fat spread was in development, one of my housemates was working for Unilever and brought back a tub of it for us to try. It tasted of soap, presumably the emulsifier. I'm not eating that s stuff on my hand baked Fergus loaf