What is your question?
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What is your question?
My 2008 Xterra has 100,650 miles. It starts up instantly, run smoothly, gets normal mileage, and all this on the original factory spark plugs. Should I replace them anyway?
You’ll actually notice a difference - spark plugs deteriorate over long periods of time and mileage - the subtle change during that time isn’t readily noticeable. Engine will operate more smoothly and have better response with new spark plugs - not a drastic change but upon next trip the improvement will be noticeable immediately. Using original equipment manufactures type spark plugs is imperative !