What is typically found in crankcase oil?

• A. Water and salt
• B. Oxygen and hydrogen
• C. Heavy metals and additives
• D. Pure mineral oil

Answer: (C)

Crankcase oil is a formulated lubricant that includes additives to protect the engine, and as it circulates it collects metals shed from engine components. The oil contains detergents, anti-wear agents, antioxidants, dispersants, corrosion inhibitors, and other additives that keep the engine clean and reduce wear. At the same time, normal operation causes wear of metal parts—iron from steel components, plus aluminum, copper, chromium, nickel, and others—so what’s typically found in crankcase oil is a mix of heavy metals from wear and the various additives designed to protect the engine. Water, salt, or pure mineral oil don’t describe what you’d usually find in crankcase oil, which is why the combination of heavy metals and additives is the best answer.