Will, your lack of knowledge on DP air brakes is showing... the majority do not have calipers. "My DP JUST sat for five months"... means since April, not all winter. If you click on "How I spend the winter" below I think you'll figure out I'm a believer that taking it to Fla is the easiest way to winterize it and rarely does it sit for five months. It's also stored inside my home so rodents have not been a problem.
I agree while under warranty you need to follow the guidelines and start oil sampling so at the end of the warranty you will know what a waste once a year is for changing the oil.