“Crude oil” is not one thing with standard specifications. It varies wildly from almost mud (e.g. Canadian tar sands) to wine like (Arabic crude). Different ref

“Crude oil” is not one thing with standard specifications. It varies wildly from almost mud (e.g. Canadian tar sands) to wine like (Arabic crude). Different refineries are configured for different kinds of crude and it is not easy to switch. So the supplier matters.