The iridium tipped OEM spark plugs in a 3rd generation (2014, 2015, 2016, 2017 & 2018) Toyota Highlander SUV with the 2GR-FE or 2GR-FKS 3.5 liter V6 engine can last up to 100,000 miles. Although they should be checked and possibly changed 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.
2014-2018 Toyota Highlander Spark Plugs Replacement Guide
