Is it true that todays crude oil is getting more 'dirty'? I heard that crude oil, which is used to make other products like gasoline, is getting contaminated more and more by atoms like nitrogen and metals, so that the catalysts have more difficulty making it clear for gasoline. If so what causes these contaminations?
We've already extracted most of the easy-to-get, easy-to-use, relatively pure, oil, and are now digging up oil from other sources, like the tar sands of Alberta, which contain a lot more contaminants than most other sources we've drawn from in the past.