Why does the coolant have to be checked for sufficient frost protection before winter begins?

You answered correctly. The coolant must be checked for sufficient frost protection before winter to prevent it from freezing (answer 1) and to avoid damage to the cooling system caused by ice expansion (answer 2). When coolant freezes, it can expand and crack parts like the radiator or engine, leading to expensive damage. Proper frost protection ensures your vehicle operates safely in cold weather. The vehicle's operating permit is not affected by the coolant’s frost protection, so answer 3 is not required. Knowing this helps you maintain your car properly and prevents breakdowns or costly repairs during winter.