Castrol 5W-50 was an approved oil for many years. My dealer used it or Mobil 1 15W-50. Both are now off the "list."
I had considered using the Castrol product during my last unapproved oil change. But I wanted to try Mobil's EP product.
http://www.renntech.org/forums/index.php?showtopic=9454&hl=unapproved