Its odd that Nitrogen compounds are considered an undesirable contaminant in motor oil, but supposedly a miracle supplement to gasoline. I have a strong sense that the nitrogen is just a small part of the detergent package that Shell is decided to make into a big marketing blitz. I also keep records of every drop of gasoline that goes in every vehicle and calculate the mileage on every tankful. Ive been doing this since 1969, so yes, I am a little nuts. I have never proven a difference among brands.

Jim