I wouldn't recommend putting diesel or ethanol in your tank.
Seriously, as long as you put premium, it should be good to go. If you do come across crappy gas, fill it with the good stuff as quick as possible. I was kidding about the ethanol, but many gas co's are putting up to 10% Ethanol. I'd prefer not putting any in, but even co's like Chevron where I filled up yesterday puts up to 10% Ethanol in their mix.
Shell has been advertising a Nitrogen enriched formula..WTF? Nitrogen is the most abundent gas in the atmosphere..as in 78%. Who the hell are they trying to fool here? If it burns, it's already in a 78% environment. Last I checked Nitrogen isn't flamable, so enriching gas with Nitrogen seems like it would lower the combustibility and reduce power. Now if they said they have been adding NOS, well that's a different story, but I'm not sure how they can add a gas like NOS and keep it in solution. Not to mention it would also invalidate just about any warranty I could imagine.
-ZCarGo-