<VV> Synthetics? Dino?

[Bill Kronen]

Hey Guys,
In all the discussion re: the virtues of lubricants, I didn't see any 
comments on the advisability of switching from one to the 
other....specifically from regular oil to say Mobil 1 or Amsoil.  Are 
there any issues connected to this that may effect an engine that has 
run all its life on crude. Would appreciate some comments from experience.
Bill Kronen
63 Spyder vert,  66 Coupe