A4 B5 doesn't let it tacker

The car of my lovely wife now has 311 tkm on it. It's a 1.8 A4. The funny thing is that even if only a quarter of a litre of oil is missing, the hydrostuttles are tackern at the start and hardly calm down. But not always. Sometimes they tacker right at the cold start, another time when the oil is warm. When I get the oil level on Max. Bring it, don't tacker it. Has anyone ever had that before? Oil pressure warning light has never been on. I have the oil retention valve at approx. 150 tkm new.