Truck just sitting?

That's what I like to hear!

Weeks or months, don't worry about it.
Year or years, do something about it.

Our truck is not a daily driver...I ride my bike to work. The truck can sit for weeks at a time all year long.
I have never used any diesel fuel treatment. Fuel at the pump is blended for the proper season already.
Truck starts right up and goes.
No worries...

Bill

after a year the diesel fuel in my heavy equipment goes funky, the machines still start and run but the exhaust is nasty smelling, Im sure its only down hill from this point.

we burn through the first tanke of fuel quickly and get onto a new tank pretty quickly so we dont worry too much about it. In my truck I would use an additive.

here is a decent read,
fuel additive clicky

google 'diesel shelf life'