Besides the mechanical problems you'll also have to worry about critters making homes in various places, especially when cool weather gets here. I had to put d-con in and around my Montero. Mice had made nests in the heater fan on 2 seperate occasions in the Montero and even once in the 4runner and i drive it everday. I found a dead squirrel under the engine cover of my mr2 a while back and a rat and a blacksnake under the hood of my 300zx several years ago. They chewed up some wiring in the Z. My vehicles become critter hotels in no time when they are parked.
Oh yeah, I also found a brids nest with eggs behind the grill of my 4runner.
I would at least fog the cylinders with something like rislone if the engine is good in his 4runner.