best weight engine oil

[bwb24 at drexel.edu (Brad Boston)]

 With the understanding that this will probably get blown way out of
proportion, I would like to know what the best weight engine oil to use
in my street car.  My baby is a '88 16V rocco and I have already made
the switch to synthetic but I have heard everything from 5W-40 to
15W-30.  I usually go a little lighter in the winter but what is too
light?  Also, because the 16V runs so hot should I go heavier so I don't
get the oil too thin on a long drive?  

Brad