If this is not the correct place, let me know; but I am going to start this from the "Other End", as it were.
I have a 2010 [Stock] GTI w/133,000 miles on it. (Bought used this past May) Drive it combo city/highway about 35 min each way to work & back. No obvious symptoms of carbon buildup issues yet. Car runs great. Almost can't tell it's running when at idle. Accelerates smoothly.
I have been noticing quite a bit of carbon buildup on the tailpipes. Comes off on your finger, so it's fresh. Does this indicate anything related to the original topic of this thread? I run 93 octane. Run Top Tier every 4th fill up, and try to do a carbon cleaning run every month or so. No oil burning at all. Looks clean, too. The tailpipe thing is puzzling. It's not a diesel...
I am told this is "normal" for a GTI. Is it really? (Price we pay for DI & the quality of the "gas" we buy?)
Could it be style of driving? I have noticed more of a tailpipe build-up since I started letting the DSG do all the heavy work of shifting, instead of using manual-mode. My overall mileage is up; but am I sabotaging myself for carbon buildup at the intake valves, and the tailpipe buildup is just an indication of that?
Or may this be related to the chain tensioner failure I had 3500 miles ago, and the bad chain cover seal that puked oil for quite a while before I caught it? Could that cause a carbon buildup at the tailpipes? I lost some 2 quarts of oil in ~800 miles before I caught the leak, but almost nothing ended up on the ground. (Not sure where it went, unless on the windscreen of the poor guy driving behind me?)
Anyway - I'm wondering what kind of an issue it might (or might not) be.
Thanks!