Hope this works!
Anyway, I almost threw this out this morning but decided to post for you guys to see. This was about 3/4 of a quart of used Pennzoil Synthetic 5W-40 Euro, that I ran in my 2014 Mercedes E350 V6 for 12 months. The engine looks clean inside, and the oil looked a normal brownish color when drained. There was only about 8000 miles put on that oil in the 12 month period. The engine has no mechanical issues, ran like a top, and gave acceptable fuel economy of about 30 mpg highway. Most of my driving is short trips, but there was a 2000 mile road trip once on this oil. The used oil sat undisturbed on a shelf for about 9 months before I decided to clean up a bit yesterday. This was the second 12 month interval that I ran with this oil, ordering it from Walmart. Prior to that Mobil 1 and Mercedes oil was used and changed regularly. The filter was changed at every oil change and nothing abnormal appeared on the filter. I also had installed a magnetic oil plug, which collected just a bare coating of debris. I have since traded this vehicle in, but it still ran perfectly, no issues.
To me, I looks like carbon was being cleaned from this engine using the Pennzoil.
OPINIONS?