Tevul Yom, Chapter Two, Mishnah Four
1) If the porridge and batter-cake were of hullin and oil of terumah was floating above them, and a tevul yom touched the oil, he disqualifies only the oil.
2) If he stirred it altogether, all the places where the oil goes are disqualified.
Section one: Since the oil is floating on top of the porridge or batter-cake it doesn’t count as being part of the larger base. This is similar to the case in yesterday’s mishnah. So if he touches the oil, the rest can be eaten.
Section two: If he mixes the oil into the porridge or batter-cake, then any part of the larger dish that contains the terumah oil is disqualified.