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

The combination of your selected answers is correct because it addresses both critical aspects of maintaining the coolant's frost protection before winter.

Firstly, ensuring that the coolant does not freeze is vital for the engine's operation. If the coolant freezes, it can lead to blockages in the cooling system and prevent it from functioning effectively, which may cause the engine to overheat.

Secondly, checking for sufficient frost protection prevents damage to the cooling system itself. Frost can cause components such as the radiator and water pump to crack or become severely damaged, leading to costly repairs.

In terms of German traffic regulations, maintaining a vehicle in good working order, especially in adverse weather conditions, is essential for road safety. Failing to address these issues can lead to breakdowns and accidents, which are subject to penalties under traffic laws.