"Matt Whiting" wrote in message
...

Why is mogas from an unknown source worse than avgas from an unknown
source?

Although I cannot cite a reference, it has always been my belief that Avgas
is subject to tighter inspection procedures from the refinery to the
customer. Also, I think that Mogas is blended more specifically for seasonal
use. If the FBO is not selling a large quantity (compared to the size of his
tank) you may get Mogas that is several months old. This means it could be
blended inappropriately for the season - or simply be just old gas with less
volatiles and/or water from condensation.

Rich S.