My family has been making wine for generations and unfortunately all
we have to show for it is some of the world's strongest vinegar. The
wine we make is all I'll drink (if I'm at a restaurant I feel like I'm
drinking grape juice) but it has a year's shelf life and then it's
just a memory. My Uncle and I have wanted to experiment with
preservatives for a long time, but my Father is in charge of the
"operation" and is vehemently opposed to it. I think he would perhaps
be more willing if I were able to present him some facts. Is it
possible to add preservatives to one bottle or must they be mixed in
with the entire barrel? Also, we make mostly (red) Zinfandel, what
should we use?

Thanks in advance.