When engine oil gets whipped by fast-moving engine parts, it can turn foamy like a milkshake, trapping tiny air bubbles inside. This foam is a serious problem because bubbles compress under pressure, making the oil lose its ability to protect metal surfaces effectively. Modern engine oils contain special anti-foam additives, often made from silicone compounds, that break up these bubbles within seconds. Without these additives, severe foaming could cause engine parts to wear out much faster or even seize up completely.