Engine damage Xantia

Hello! My beautiful Xantia (2.0 petrol) unfortunately had a bigger breakdown on the weekend. On a motorway ride there was a funny noise (a clack) from the engine compartment and the oil temperature went up. I stopped and called the ADAC. He moved immediately with the tow truck. Diagnosis of the ADAC employee was no oil! But that could not actually be. Otherwise the car would have used up to 8,000 km 4 liters of oil. I then filled 2.5 liters of oil and am to a workshop of one The sound was back and performance was not normal either. The water temperature is normal and the engine compartment is totol dry. Do you have any idea what all this can be? Greeting Jörg-Peter