s a big mistake, spark plugs are not eternal, wear out ...
of copper, are changed every 6000 miles ....
the Iridium every 25.000 miles if you use nitro or turbo, you should change it to half the use by abrasion ....
and platinum are changed every 60,000 miles or so ....
any material or plug is eternal, especially if subjected to combustion in an engine pressure are extreme conditions, see how mine are the stock at that time had only 6,000 miles, that wear causes a spark of poor quality ...
Change them and take a picture for you to realize or current ...