Robert has said many times that he doesn't see that the US is processing more heavy sour crude than we did 10 years ago, so I believe he doesn't think it's a factor

One more time, this is not what I said. There is a clear trend toward heaving and more sour crudes in the past 10 years. My point is that the quality has been relatively stable for a least a few years. In other words, we didn't suddenly develop refinery problems because we are suddenly processing poorer quality crude. The crude quality is almost identical to what it was 2 years ago. That's according to the EIA statistics.

OK, sorry and apologies, but still the EIA stats are not showing a sudden drop in quality of crude entering the US refineries.

Wish I knew what percentage of the refineries in the US could handle what levels of crude quality and what kind of runs they've been using in the last three years. It would be interesting to look at it on a refinery by refinery basis to see if there are any patterns.