What is in crankcase oil?

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

Answer: (D)

Crankcase oil isn’t just pure base oil. It’s formulated with a variety of additives that give it the protective properties engines rely on—detergents, dispersants, anti-wear agents, antioxidants, corrosion inhibitors, viscosity modifiers, and more. As the engine runs, wear and corrosion shed metals from bearings, pistons, and other components into the oil, so used crankcase oil contains heavy metals such as iron, aluminum, copper, chromium, zinc, and other wear metals. Put together, the presence of these wear metals along with the packaged additives best describes crankcase oil. Water contamination can occur but isn’t a designed component, and pure base oil wouldn’t include the necessary additives.