Oil consumption..can this explain to me jmd???

Hello, as I already wrote here I repaired the engine from my astra (C16nz).. Now I have the following problem, I have driven since about 1400km. When I changed zkd and zk also took part in the oil change. Stand was then at max. then 400km driven, oil level checked, then he was only about at the half, well I didn’t think about anything and felt up on max.. then this morning after I drove about 400km again looked after, oil level was thism al under min!!! approx. n half cm. I drove today 2 times 300km at the piece.had refilled and oil level checked about all 100km on the ride.. this time he lost nothing / consumed, looked again when I arrived, and oil level was the same as I started??? The km before I always drove short distance so about 30 to 40km, and today the 600km.. can the jmd explain to me???