My Caddies were about every 11 months.  They took an extra quart that added some cost to the change.  The GTI was about the same, also with 6 quarts.  The Corvette 6.2 may have 8 quarts, I don't know for sure.  The Hyundai is running about every 8 months.  The first four are free and then they are pricey at the dealer.