Massive oil loss

My Lupo 2003 1.4 base lost massive oil 3 weeks ago, during the ride, after a frosty night. The oil lamp lit up and my daughter, as a driver, could still take the highway descent and drive to the gas station. There she noticed that the motoblock was full of oil. We then had the car towed and brought to a PIT-stop workshop. The engine block was cleaned, 3 liters of oil was refilled and the engine started. It is hard to believe The owner has no explanation and now I drive the car again. I have already driven about 200 KM and everything is tight. The outside temperature is in something like us in case of damage. At VW I had asked for a possible recall action, however, there were none. Who has an explanation for the oil loss. My daughter has to go back to work with the car from Tuesday and the work place is about 30 KM away and mainly highway. ch over every tip Detlef Benning