2016 Sorento SXL
Based upon what test and what metric? I know of no owners of a 3.3L GDI Kia/Hyundai engine that have had need for anything approaching 10K intake service. Other manufacturers' engines are FAR more prone to this problem, and would be better candidates for that advice.Your mechanic is correct, it basically needs to be done every 10,000 miles
"... from a few manufacturers."
And has he had a look inside a Kia to confirm it suffers from this kind of issue early on? As noted above, there are some (not all) other makes whose GDi engines have major carbon issues, but not seeing it on these particular GDi engines.