The iridium tipped OEM spark plugs in a 4th generation (2014, 2015, 2016, 2017 and 2018) Subaru Forester with the FB25 2.5 liter four cylinder boxer engine can last up to 100,000 miles but they should be checked well before that mileage. Take a look at my DIY instructions for the procedure (with the compatible replacement part numbers) by clicking on the text link or thumbnail image below.
2014-2018 Subaru Forester Engine Spark Plugs Replacement Guide
