Good quality: WTI is considered a "mild sweet" crude oil, which happens to be easier to refine, although Brent can be a combination of crude oils, together with equally "light-weight sweet" and "major sour" grades. Screening is by references that POs talk to each other for, not by released assessments https://limawebdirectory.com/listings795850/the-smart-trick-of-oil-that-nobody-is-discussing