2017 Hyundai Sonata 2.4L GDI engine in signature calls for OCI of 3,750 (severe) and 7,500 (highway) with 5W20 , 5W30 or 10W30 allowed (depending on ambient temperatures) . *Thinking about doing a 10,000 mile OCIon a GDI engine - I say think again : The first reason is the fuel dilution issue of GDI engines as by 3,000 ~ 4,000 miles after an oil change - it becomes a significant consideration . The 2nd reason is due to the increased impurities a GDI engine creates which ends up back in the oil which I believe find themselves in the vapors that land on intake valves and create carbon deposits which are difficult to clean . Additionally , I'm not sure even a Blackstone test with TBN measurements tells you all you need to know IF you drive a GDI engine - the fuel dilution number may be the most critical . So , I say if you drive a GDI engine - only use synthetic in the recommended rating , with the lowest NOACK and error towards reducing your OCI's rather than extending them ... Your thoughts ?