The thing that sticks in my mind is:
Do frictional losses in an engine account for 15% of fuel consumption total? In other words, if we used pure unobtainium dust in our oil and made a windage tray inspired by the lord himself and cut internal friction in the engine to 0 would we pick up 15% more fuel economy. And honestly I dont know. But I doubt it's hitting say 20%. I think internal engine and driveline friction accounts for 15% max. If it were otherwise we would all be running at 300 degrees coolant temps due to the energy being transfered into heat due to friction. So that must be one amazing lubricant.