Pam cooking spray will last longer than WD-40. Pam is an actual oil, where WD-40 is not and will eventually evaporate.
I also add a container of Damp Rid to control moisture and plug the exhaust and OAK (to prevent any actual air infiltration).
Then put a little note in the firebox, to remind yourself to unplug OAK and Flue before 1st fire.
Preventing rust will lengthen the life of your stove. Trucks rust out every year. Only a matter of time before a stove does. I take any preventative measure I can to prolong the life of all my stoves.