In oil coolers, the hot oil transfers its heat

• A. By conduction to the engine block
• B. Through the oil filter
• C. By radiation to surrounding panels
• D. Directly to the air and/or coolant

Answer: (D)

The hot oil gives up its heat through a heat exchanger to the surrounding cooling medium—air and/or coolant. In an oil cooler, oil flows through a core with metal walls and fins, so heat moves by conduction from the oil into the cooler walls, and then by convection to the coolant or to air. This keeps the oil temperature in check and protects the engine. It isn’t primarily conducted into the engine block, and the oil filter isn’t a heat-transfer path, while radiation to surrounding panels is negligible in this system.