The iridium tipped OEM spark plugs in a second generation (2010, 2011, 2012, 2013, 2014, 2015 & 2016) Buick LaCrosse should last up to 100,000 miles but they should be checked before that time. Take a look at my DIY instructions for the procedure (with the replacement part numbers) by clicking on the text link or thumbnail image below. (The steps should be about the same for the LLT or LFX variants of the GM 3.6 liter V6 engine.)
2010-2016 Buick LaCrosse 3.6L V6 Engine Spark Plugs Replacement Guide
