RE:321 Crack Spread plummets 50% in 30 daysCrack spreads are definitely a concern. Obviously end demand is a big input into prices. Suncor cracks oil so it definitely is worth considering. It has bearish overtones.
One the other hand the markets are getting further into fairly signifigant backwardation. This is the Saudi effect. Despite lower cracks the physical market is tight and getting tighter. This is a strong indication of demand for raw crude.
from @HFI_Reasearch (read his twitter and consider subscribing to his newsletter if you like great analysis)