Which do you think would be a better month to change the oil in ones backup generator, June or December. This is not a trick question. Only a moron, or the author of this blog, would choose to do this on a bitterly cold and windy day. Still, better to take care of this basic maintenance task than to be left without electricity in an emergency situation. I also ordered a thermostatically controlled battery heater from China which should arrive in a couple of weeks at which time I will pose the question; January or July.