Oil problem

Hello dear motor talker, I have a real drama again with my omi and now have no idea any more. Hopefully someone can give me some good advice. So I got a 95er 2.0l 16V Omega B. I got it back out of repair at the end of November. The head seal was defective. So in the last 4 months exhaust manifolds and gasket were renewed. Head seal, pulleys, pulleys and timing belts are now also new. The cylinder head was planned in FW and the valves new e Then he got new valve shaft seals. Now the thermostat was over, he has also new. But the anger does not tear off. Now he has an absolute oil burner. He does not smoke much from the exhaust but after approx. 500KM I have to refill every time about 0.5l oil. I don’t understand that completely. Especially since he would have to smoke much more heavily with this oil consumption. Does someone have a advice what I can do. How does he burn so much oil now??