This is just weird! Some people/places get them all out without breaking any, others ..., well you all know the story! There's got to be some common thread in here that explains why some break and others don't.
I used to think maybe changing them earlier, say at 50,000 miles was insurance against breaking, but that doesn't seem to hold up. Then, I thought maybe people were a bit impatient, and that caused the problems. But, again, too many people have said they were super careful! I have to believe at least some of them were.
I still think that since carbon buildup is the cause, perhaps trucks that are driven mostly on the highway are more apt to have the plugs come out in one piece. And, if this is the case, then more frequent changing of plugs in trucks driven mostly in the city would seem to be a good idea.
Be nice to know anyway. You seem to save a lot of money and time if they come out without breaking.
- Jack
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