[pyx]

The supply problem stems from the fact that two of the refineries that produce Phoenix's unique oxygenated winter fuel have been shut down.

I am asking out of ignorance about the purpose for this fuel formula; Is this oxygenated winter fuel sold specifically in this area of the country used during winter because of the thin oxygen in the higher mountain areas and therefore increases the burn rate of the fuel ?

And if not, other than simply ambient temperatures generally rising, what changes occur in the area on or about April 1st of each year that necessitates a fuel formula change ?

[HiJinx]

Not sure I have the right answer, but it has something to do with air movement during winter months...

The oxygenated fuel is supposed to burn with less exhaust emissions, therefore is supposed to put less pollutants in the air, which isn't moving as much and can't get rid of more pollutants.

Which doesn't matter any, anyway. If you've ever driven into Phoenix, you'll know what I mean. You can always tell where it is, from over 100 miles away, just by looking for the muddy brown soup that makes up the air over the city!

[kaktuskid]

April is usually the end of winter inversion season...and the beginning of ozone season