The oil fires should not be sprayed with water. Why?

Oil fires are caused when oil catches fire accidentally. The use of water to put off oil fires is not suitable. This is because water is heavier than oils. If we spray water in case of an oil fire, water will sink below the oil and oil on the top will keep burning. So in such fires water can’t act as a barrier to cut off oxygen supply and thus oil fires should not be sprayed with water.