JB, those could be spec'd to have crank case heaters, or you could just be lucky.
If the units are not off long enough for the motor to cool down, then the migration process won't happen. I have operated bunches of units in cold weather, but I have also been there when slugging takes place and just the noise is enough to make you run for cover!
I see you are also down in Tyler, the warmer the climate, the less the chance of liquid migration. Of course if you keep the fire house really cold, there will be less temperature difference between indoors and outdoors.
Bottom line, I don't know in this case.