Replaced spark plugs, most of them came out clean but 5 and 7 looked as per picture. The D2 runs smoothly and no codes, 64k miles, I just did HG couple thousand miles ago, no leaks, no ticks, pretty clean.

any suggestions on what could be causing it? I’m thinking injector problem? Not sure.

 

If mostly short trips around town, maybe try one step hotter plug at 7. Seems to be a bit of oil burning to me. Maybe from the PCV system? Maybe valve stem seal not sealed? Perhaps keep driving and check again after 3000 miles. The good news is the others look great.