If price is no object than there really is no downside to using a full synthetic.
I regularly run Mobil 1 Extended Performance 5W-30 or Mobil 1 Racing 0W-30 in the Mustang. I have been doing used oil analysis on the Mustang for years and they always come back with glowing reports.
I just had a used oil analysis done at 102K with an oil change interval of 7500 miles. The Mustang does not burn a drop of oil and the results again were positive with below normal wear and no water, fuel or solids in the oil and plenty of additive left with a TBN of 3.0 (TBN of 1.0 is considered low).
If you have questions about your oil than I would suggest used oil analysis. I use Blackstone labs and would recommend them to anyone.
Blackstone Laboratories