The cohesion forces between water molecules are stronger than the cohesion forces between oil molecules because water molecules are polar, meaning they have a positive end and a negative end. This polarity allows water molecules to form hydrogen bonds with each other, which are strong intermolecular forces. Oil molecules, on the other hand, are nonpolar, meaning they do not have a positive or negative end. This means that oil molecules cannot form hydrogen bonds with each other and the only forces holding them together are weak van der Waals forces. Therefore, water has stronger cohesion forces between its molecules than oil.