I have an '07 Hemi Ram with 138k on it. Manual recommends replacing the 16 plugs every 30k. I replaced mine at 110k and it looked like the factory originals - electrodes badly worn. But the porcelain was a very light tan color. Corrosion was evident On the plug threads. I used anti-seize on the threads of the new plugs that cost $0.99 each.