The old Jetta oil cover has milky white and water droplets. What happened? Is it serious?

After the coolant is mixed with high-temperature engine oil, it freezes when it is cold at the oil filler. The problem is not serious.

In the morning, when the car is cold, open the cover of the gas filler and observe whether there are milky white water droplets in the cover. If there is no water drop when the car is cold, run for a while and take a look when the temperature rises. Check continuously for one week, and observe the coolant level in combination. If the liquid level of the car is different when it is cold and hot, record it separately (draw two lanes with different colors). If this phenomenon does not appear during continuous inspection and the coolant level does not drop significantly, it can be operated safely for a period of time. If there is a significant decline, it needs immediate maintenance.