I do 5,000 mile oil change intervals with Mobil-1 and have had Blackstone oil analysis reports done 6 times over 100K miles (see
this post).
My TBN numbers consistently show that my oil has plenty of life left in it at 5,000 miles. 7,500 miles would not be a problem. The only reason I do 5,000 miles is because it's easy for me to remember and I rotate my tires at the same time. From a purely financial standpoint, I am draining usable oil from my car at every oil change.
If you're concerned about how your oil is
really doing, spend a couple of bucks and get an oil sample analyzed after you have racked up some miles.
Whatever you do, just keep good records and receipts so if something does blow up under warranty (not very likely in these cars), the dealer won't use "lack of maintenance" as an excuse.