bluestar,
Don't worry too much about the gasoline if it is in a totally sealed container. Once you put it in the mower, however, it begins evaporating from the fuel bowl. As it does the float lowers and allows more into the fuel bowl.
In this way only part of the gas evaporates from the fuel bowl leaving behind the varnish. That's why you use stabil or something for storage over the winter while the engine is not being run for extended periods.
If your gas container cannot be sealed up, then use stabil in the gas can also IF it is going to be kept for an extended period.
As mentioned earlier, most gas additives do nothing but make your wallet thinner, but you do need something to get the fuel through extended periods of more than a few months and stabil is a good choice.
Also, I don't know if Stephenville is far enough away from the DFW Metromess that they do not have reformulated gas. In the DFW area reformulated gas is required to be sold there. Reformulated gas has LOTS of additives already in it. With reformulated gas you really don't need to add anything.
I live to the East of the metromess in Lamar County and we do not have reformulated gas. I try to fill my car or truck up when I am in the metroplex so that the additives will keep my fuel systems clean without buying aftermarket additives.
As a veteran myself, I know what DAV means but I don't know what UC stands for.
Take care of all the pets and we'll talk later,
Doc