I haven't found that to make any difference myself. This is a mechanical problem, not a fueling issue.

It's not detonation from pinging.

 

You mention transmission flairs? What were you experiencing? Recently on occasion noticing some hesitation etc. normally lower gears when accelerating. Just curious. Its an 07 CPO so will be addressing that plus dash rattle when next oil change. Dash rattle not as bad now with warmer temps, but don't want to go thru that next winter. This year was worse than 1st year we owned. As for this post on engine during cold start ups. Ours not that quiet either. We use reg. gas since that's all the dealership uses in their CPO's etc. Still get 22-23 around local and 32+ on trips which i think is pretty good for a V6 and car of this size etc.