Because Pennzoil sucks probably more BMW’s burning crazy amounts of oil . That why I went back to Mobil 1 no more burning for me.
I was going through 1/4 of a quart of PP Euro 5W40 in 1,000 miles. No consumption so far with M1 0W40 and I did track day where I sent engine into limp mode due to high oil temperature (90 degrees + high altitude are really bad combo when one does not have oil cooler).I wouldn't go that far but in a way you make a valid point. Some users report higher than usual oil consumption, nothing against the brand and I have no answers or theories just questions.