The effectiveness of an oil cooler depends on various factors including its size, design, and placement relative to airflow. For F6 engines, air-to-oil coolers are commonly used due to their efficiency in transferring heat away from the oil using ambient air passing over finned tubes or stacks. An air-to-oil cooler must be sized appropriately for the thermal load of the engine and positioned where it receives sufficient airflow, often at the front of the vehicle or near ducts that direct air over it.