Two of the big wear items that people forget about until they fail are 1.
Hoses, 2. Radiator.
These are often overlooked and could prove fatal if they failed when a friend
or someone was driving the van who wasn't paying attention (let it overheat
and then toast city).  Hoses just go bad with time.  The rubber just gets old
and I would say that 10 years is probably the life limit on rubber hoses no
matter how low the mileage is.  Actually the more the van sits the worse it is
the the rubber because dry rot sets in.  If you are in a high salt area or if
your vehicle has a bunch of miles on it the radiator is another life limited
item.  With all the expanding and contracting and pressure on them and heat
they just wear out over time.
Do a visual exam of the radiator at the lower corners to check for corrosion.
When I went to buy a new radiator for my '84 Vanagon a couple years back every
body wanted $250 for them.  Well I get a good deal on the ones I sell so I
will pass it on to the list.  Mine are OEM replacements not aftermarkets.
They are $175 + shipping.  This covers all years and models of watercooled
Vanagons including diesels.
Ken Wilford
Van-Again
John 3:16