Half of spark plug are bright red on insulators

175,000 MILES • 5.9L • V8 • 4WD • AUTOMATIC
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WAYNERAGE54
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Today i decided to change the spark plugs on my truck and i this is what i had when i was finished. all four on driver side bright red all the way around insulator and red on the electrode, and on passenger side: 1 fouled, 2 very black on insulator, and 1 with a red like the driver side but just halve of the plug. I have used no additives in the gas and i have been running unleaded and occasionally mid-grade and have never run into this issue before, except once when all of my passenger side fouled at the same time one day leaving school. Any advice would be much appreciated.
May 31, 2016 at 2:35 PM
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HMAC300
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  • 48,601 POSTS
hard to say about coloring it may be fuel additive that gas station has put in. As far as the fouled one keep an eye on that one and for the black that can be from short hops like under 10 miles or so where you go to the store shut it off then start and go back home repeadedly
May 31, 2016 at 11:42 PM
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WAYNERAGE54
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So earlier i went to do a quick check to see how the new plug in cylinder 2 was doing and its already worn after being drove just once and the others are all fine
Jun 1, 2016 at 12:31 PM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
if you are talking about the plug on the left in pic there is nothing wrong with it. the other plug on right looks pretty good as well. if these are going into aluminum heads make sure to use anti sieze on plug threads.
Jun 1, 2016 at 11:49 PM
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