In a message dated 4/10/02 11:06:24 AM, VW85Westy@AOL.COM writes:

<< Air enters cooling system
during highway driving. >>

This is impossible because while driving, the coolant is at a positive gage
pressure, even with a leak.  Have the coolant checked for combustion
byproducts.  If there is any present, then you have a combustion leak of some
sort.  The real problem is getting someone to pay for it.  You certainly have
already made your contribution in that department.  One thing which puzzles
me: did not $600-worth of diagnostics reveal anything of substance?

Rich