Just wonder if any using Royle purple has seen any improvments in MPG. I have 11,000 miles on my truck and this is the 2 oil change i have done. Both times i used Royle Purple. I check every tank of gas that i run to see what my MPG is. Most of the time i get about 17-18. But since i changed my oil this last time it keeps going up. The last tank of gas a ran i got 19 MPG and this one is at 21 MPG so far. Anyone else having any luck with Royle Purple.