Check the sides of the engine to determine where the leaks may be coming from. I had the pleasure of doing this in my wife's X3.
If oil residue is visible on the engine block facing the passenger side, you have a valve cover gasket leak. I replaced the VCG two years ago because of a small leak.
If oil residue is visible on the side facing the driver, you could have a leaking oil filter housing gasket (OFHG) or CCV. I cleaned the engine block thoroughly and watched for oil residue to determine where the leak was coming from. After some spirited driving, it was clear the OFHG was leaking. I had this changed at the dealer because I didn't have time to do and I got a X1 loaner
good luck