My wifes Audi A4 quattro uses the oil filter with a stud Jimmy_Russell pointed out as did a VW GTI I once owned. I've had the stud and plastic ring stay in the engine block a few times on both cars. The oil filter mounts on top of the engine and when everything goes good, you don't drip a single drop. Switched to Mahle and never had it happen since. Here is a pic what happened to me.