I had a plug that had some ash on it like that, and probably not coincidentally I think my car has bad valve seals. The electrode was not white like yours however, which would suggest excessive heat or running lean. I assume it's a colder heat range plug for the spray? If you just did valve seals and there's still evidence of oil it might be worth doing a compression check just to rule it out, although you might be down compression anyways from the life that motor has had.
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