New for 2018 is Form I-385 is used to compute SC credit on Form SC1040 for eligible vehicles. Instructions refer to "regular maintenance" and "preventive maintenance." Two questions: Do extended warranty costs qualify? And do normal repairs qualify? Unable to find anything in instructions or SC Revenue Rulings which mention these in particular. Tires and oil changes are specifically mentioned. I would assume changing of transmission fluids, or new batteries, etc would fall under "regular maintenance" or "preventive maintenance" if performed in SC.