Have that same year Soul, 2010, bought Dec. 2009, 2L with only 65K on it; original owner; use Mobil 1 5W20, change every 4K miles, have replaced engine coolant and trans fluid with KIA brands at 55K; my only issue are dead batteries in the TPS sending units in each tire - no worries; minor rattle somewhere in the rear - some say that is a loose linkage gizmo in the rear suspension - Happy Camper.
Out of curiosity, looked up info on the newer generation GDI engines and found this using Google:
GDI, or gas direct injection engines, are great engines, but they need a bit more periodic maintenance. If you drive one of these vehicles, this is important. Because of their design these engines need treatment with CRC GDI IVD Intake Valve Cleaner every 10,000 miles.