[August]

OMG don't get rid of the horse!

While, depending on several factors, there may be an ample gas supply it will eventually run out or become contaminated. The way I figure it, surviving the zombie virus will be easy enough, basically fort up until they eat up their available food supply and die off, maybe wait a few months after that to let the corpses decompose then all you have to worry about are the savages.

It's because of that and the loss of modern conveniences that will make surviving in the long term the real challenge. In that horses and other low tech things will be vital.