The discussion is not cheap oil etc

It is a scientific question: is Kirkland as good as "Euro" oil or Castrol Edge?
I have used all kinds of oil, Kirkland, Napa Synthetic, Castrol 5W40 etc etc over some 20 years.
You will soon find out there is no difference.

The most important part is not the oil, it is the interval...I stick to 5K ---> 7.5K mile interval.

Right now, I am using Castrol Edge 5W40 bc the name sounds "sexy" lol...
And Castrol 5W40 is at $26 or so, roughly > $5/qt vs Kirkland at $3.70/qt.
Kirkland stops at 5W30, they don't have 5W40.

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT