There's been very few responses in this thread claiming more engine noise with Mobil 1 or Mobil 1 Extended Performance than with other oils. This surprises me, in view of the long-standing numerous claims on here of noise with those oils. Perhaps a lot of those who formerly claimed that the Mobil syns caused noise have changed their minds.
I also think that most claims of noise with the Mobil syns are bunk, just as I think that most claims that the engine runs smoother, or you get increased acceleration, with a given oil, are objective, seat-of-the-pants, bunk.
I'll bet that you can take ANY conventional or synthetic oil made by any oil company and find people that claim that it causes engine noise versus other oils. If so, it means that: (1) most of those claims are bunk; or (2) increased noise is a possibility with any oil, not just the Mobil syns, so you can't criticize the Mobil syns; or (3) both of the above.