Can spark plugs really go 100,000 miles before being changed?
A. I have heard of spark plugs found seized in cylinder heads of vehicles with as little as 60,000 miles. It took over four hours’ labor just to remove the plugs. There are documented cases where it was necessary to remove cylinder heads just to get the plugs out. Experienced mechanics suggest that to maintain peak performance, spark plugs should not be run longer than 30,000 miles, even though they continue to fire. Car buyers should take those “100,000-miles” marketing claims of manufacturers with a grain of salt.
