The iridium tipped OEM spark plugs in a 4th generation (2018, 2019, 2020 and probably also the 2021, 2022 & 2023 model years) Ford Expedition SUV with the EcoBoost 3.5 liter twin-turbo V6 engine can last up to 100,000 miles but they should be checked and possibly changed before that mileage. Check out my DIY tutorial for the procedure (with the OEM and compatible replacement aftermarket part numbers) by clicking on the text link or thumbnail image below.
2018-2020 Ford Expedition EcoBoost 3.5L V6 Engine Spark Plugs Replacement Guide
