USLD has been one of the best things ever to happen for the diesel engine, its all of the EPA mandated controls that are hampering the overall effiecency.
UOA's have never been as good as they are now, and USLD, along with better lubes, are contributing.
I'm all for lower prices, I don't have an answer as to how to do it though. The demand is increasing every year for fuel, whether it be overseas or here in North America.