So this is one of those deals that won't apply to 99% of Slickdealers because you have to live around the DC Metro area, but Fairfax KIA in Virginia always does free oil change for KIA vehicles no matter if you bought the vehicle from them or buy any other services there. In fact, in the three years I lived in DC I never once had them do any other paid service to my vehicle and they were always polite and would wash the car after the oil change as well.
You can schedule a free oil change by visiting https://www.fairfaxkia.com/schedule-service.htm
Let me know if you have any questions and please don't downvote because you don't live in that area. Thanks.