According to kiapartsnow.com it supersedes 26300-35504 which BTW superseded 26300-35503. As to whether 35505 is an improvement over 35504--who knows. I've used 35504 for my first 5 (soon to be 6) oil changes and AFAICT I've had no problems so far that could be tied to using 35504. As turbonut said, it could be simply a different supplier/manufacturer--I can't imagine Kia actually manufactures/assembles their own oil filters.