That is the first thing that I did. Matter of fact, I called them twice, the first time I was told SEMI - synthetic and the second time I was told FULL synthetic! Turns out after talking to a Kia rep. Semi was used in my K5. Finally, after 2 calls to the dealer, asking here on the K5 forum and talking to a Kia rep, I finally get a answer from someone that knows. It's SEMI - SYNTHETIC!! YEA!Why not just call the DEALER and see what they use in your model?