What fluid is typically used for a car's cooling system?

The fluid typically used for a car's cooling system is a mixture of antifreeze and water. This combination plays a vital role in regulating engine temperatures, preventing overheating, and providing adequate heat transfer during engine operation. Antifreeze, also known as coolant, is designed to withstand extreme temperatures, preventing both freezing and boiling in the cooling system. The addition of water helps in efficiently transferring heat away from the engine, ensuring optimal performance and longevity of the engine components.

In contrast, oil and water mixtures are not suitable for cooling systems as they do not offer the necessary thermal properties and can lead to engine damage. Windshield washer fluid is formulated for cleaning windshields and does not provide any cooling properties. Brake fluid is specifically designed for hydraulic brake systems and has no role in temperature management within the engine. Therefore, the correct answer reflects the standard practice in maintaining a vehicle's cooling system effectively.