The iridium tipped OEM spark plugs in a third generation (2014, 2015, 2016, 2017 & 2018) Mazda 6 sedan with the SKYACTIV-G DOHC 16V VVT 2.5 liter inline four cylinder motor should last up to 100,000 miles, but they should be checked well before that mileage. Take a look at my DIY tutorial for the procedure (with the compatible replacement part numbers) by clicking on the text link or thumbnail image below.
Mazda 6 SkyActiv-G 2.5L I4 Engine Spark Plugs Replacement Guide
