<VV> Concerns about using the latest rated oil in pushrod

[Stephen Upham]

          <snip> It looks as though we can't go to just any store and  
buy the correct oil for our cars any more. In fact I just acquired 3  
cases of SL oil from a friend who thought it was out dated.
                      Paul Fox

I have 24 cases of synthetic oil from the late 70's that my father  
ran in my sedan as late as '93.  I have never used the oil in any of  
my cars as it is rated for cars built before, I believe, '86, and is  
dated to boot.  I am wondering if this oil is a viable alternative to  
the problem that we, as owners of vintage engines, face as it was  
manufactured for cars of the Corvair's era.  This is a new rebuild  
that has taken more time and money than I can easily relate.  I want  
to make sure that I'm doing EVERYTHING that I can to insure its  
longevity.

In short, does synthetic oil go bad?

Stephen U