Oil level changes frequently
 

This is my first BMW so maybe this is normal, but about two weeks ago I got an "Engine oil level below minimum" warning which was a shock because probably once or twice a week I will check the level in iDrive and it is always full.

Since then I have been leaving the oil level screen up on the iDrive screen and have noticed that it fluctuates all over the place. I typically do my testing while driving but I've also done it on flat ground. I've attached some pictures so show the various levels I've seen over the last couple of days. Is this normal? Am I missing something here? The part that scares me is that sometimes it'll show that it is full, other times it shows just above the minimum line. I don't want to add oil if it's full but at the same time I don't want to run low.

When I check the oil level I am using the suggested process in the owner's manual by driving it for "at least 6 miles".
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