I've been using Arco for years with no issues. Every now and then I'd mix things up by trying another brand or grade of gas to see what it would do to my fuel economy (because really, with little 4-bangers, there was going to be no noticeable performance difference).
What I've found, at least in my experience, is that brand doesn't make a difference for fuel economy. Fuel grade *does*, but unlike some threads I've read in the MPG forum, my fuel economy goes *down* every time I use premium fuel. So, based on my experience, it's counter-intuitive to use anything higher octane than the manual recommends.
Also, the Shell next to my house is 30 cents/gal higher for regular unleaded than the Arco down the street, and the price disparity gets worse the higher grade you go.
That's not to say that I've never had a fuel-related problem in my driving experience. I had a set of injectors get clogged and die back when I was regularly using Texaco (top tier!) gasoline. Coincidental? Possibly. But it's just my experience.
