Parking truck for unknown timeframe

I'd fire it up and let it hit operating temp every month or 2, maybe drive it in circles in the yard a little bit or something. Seen more than a few just simply get parked until needed or sold too. Doesn't usually take much to fire them up then either.

 

I have several in long term idle, I have the brakes caged, oil changed IF close to the oil change time, pull the batteries all out and put them in warm storage with a charger made for long term storage (not a trickle charger), clean the cab and sleeper up then put mice traps and spray mint concentrate all over the cab/sleeper - which gets checked on every few weeks. I also add a biocide to the tanks of which if they sit for more than a year, I have the fuel polished with a filter setup to remove the condensation water and crap that has grown in the fuel. There are companies that will polish the fuel, this is done on boats with diesels to clean up the algae and contaminates that accumulate in the boat's tank.

The engine is pretty well protected by the air cleaner/turbo setup from moisture, I have yet to have any issues with an engine or the drive train when they sit for more than a year or two. I never see any water in the oil.

I have three that I moved out of Detroit to the new place, they were sat for 4 years, one is my problem truck which I took a huge financial hit on and can't get rid of yet. They all started up once the brakes were released and the batteries were installed, they all were moved without any issue but the drivers all complained they didn't like the smell of the mint spray which is really strong and works really really well in keep rodents and panhandlers away.

 

I would disconnect all the batteries so nothing draws em down. Clean and seal up the truck so nothing gets inside. You don't gotta start it monthly or anything won't matter. Just when getting ready to put truck back in service either charge up those batteries or just replace. Then clean truck and check for leaks and what not

 

Trucks are meant to be used.
The longer since the last time it was used, the more will need repair and replacement.
Especially true on older trucks.
Let me put it like this. If a truck was sitting for two years, I would put the value at scrap value.
They dont age well.