The iridium tipped OEM spark plugs in a 4th generation (2016, 2017, 2018, 2019 and 2020) Kia Optima sedan with the Theta II 2.4 liter GDI inline four cylinder engine should be replaced at 105,000 miles according to the owner’s manual. Although they should be checked and possibly need to be changed before that mileage. To view my DIY tutorial for the procedure (with the compatible replacement part numbers) by clicking on the text link or thumbnail image below.
2016-2020 Kia Optima Spark Plugs Replacement Guide
