Ron Rosenfeld wrote:

One problem is that frequently, after sitting around for a few years,
there isn't fresh gas in the tank! (I should have been more specific
as to the reasons).
--ron

My 40kw runs on Natural Gas or Liquid Propane and is configured to
automatically switch between them. No worries about fuel geauxing bad
from evaporation or sucking moisture out of the air. Course those fuels
aren't cheap either, but it sure cuts down on the hassle factor of
trying to buy gasoline/diesel when all the retailers don't have power
for any length of time...

Spent over 60 hours on a 5.5kw due to hurricane Lili (6 gallon tank,
used 90 gallons), it eventually burned the muffler off (bought it new in
'85). Needed the 40kw for only 18 hours during/after Rita (didn't even
get a drop of rain from Katrina) and it makes my UPS's very happy too
when needed. Now I can cook and enjoy airconditioned comfort while my
neighbors ice boxes are also plugged in as well...

If I had to buy another portable, NG/Propane would definitely be high on
the list for compatible fuels. Just remember you lose some power output
when using those for fuel...