I don't want to get into my Shell rant, but imho its total crap. I really noticed that fact with my Supra Turbo, which is finicky with what 93 octane fuel you put in her. It would pull timing so much earlier with Shell then with Sunoco or Irving(which is only available in the Northeast). So I began to pay attention in my other vehicles. In the end, I'd put Shell on par with costco or sams club fuel. From a marketing stand point they are the leader. After all to convince folks that an element with a -320F boiling point could be in their fuel to benefit your engine, pure genius. My wife when she fuels up my GTI will often go to Shell because its more convent for her, she has been briefed not to do so. I notice almost immediately, as my MFD will show a 2mpg drop from my normal dose of Irving fuel during my daily commute. She can't believe I can tell the difference. In fact its led her to try and trick me and see if I notice. I notice every time. Believe what you will, but track different fuels by MPG, Shell, always in my Titan and GTI come up short vs. everything else. If you loose MPG with a fuel your running richer, and less timing, more crap cycling through your EGR equating to more carbon. Nitrogen, what a scam..... I can't fault their diesel in my TDI though, seems on par with everything else.
