This has been such an informative thread. Thanks to everyone's comments. I have a "surrogate" grandson that has just been diagnosed as "mildy autistic". This next while is going to be a very busy learning period for his parents, and for my DH and I as Gramma and Grampa. This little guy LOVES it when DH or I take him for tractor rides. He was so disappointed last week when he couldn't go for a ride...it was about 10 below, with a wind chill to about -35!!!!