Yeah I'm used to getting them, but I actually owned the vehicles for the time I am charged for. Plus they are only like $25 a piece.
I idle more in the winter. I do not have an A.P.U. and run Michigan all winter. I have to idle while I sleep to stay warm. I think you will find it is very common to get better fuel milage in warm weather.
Without additives the summer blends will. Got be careful buying fuel in the south then running north. Also the new ulsd diesel is gelling bad even with additives. Lots of froze up trucks last year