I doubt very much that Delco is the problem, but by all means replace it
with one that doesn't go dead often. Have you checked it for a drain on the
battery? You may be replacing a battery with a dead or bad cell and then you
can be right. Of course you can be replacing the good battery with a good
battery and gain nothing. My truck with a Delco battery sits most of the
summer and the battery doesn't go dead often. My 72 sits more than it should
but I can only drive one at a time and the Delco doesn't go dead often.

I've always had good luck with Delco, but my friends prefer the
Optima.  You might want to get a "Battery Tender or a "Battery
Minder".  Either one should prolong the life of the battery if it
sits unused for long periods.
http://www.batterytender.com/
http://www.vdcelectronics.com/index.htm
John

Delco is a fine battery.
it may have run its life.
if not ?
you have something gone wrong that may be pulling it down.

my2¢

Sounds like you've got stray current somewhere. Even with a 4 year old
battery you should be able to weather 30-45 days with just the radio and
security loads.  Might be good to tackle that problem before exposing a
new Battery to a damaging condition.

My Delco experience has always been good.  Exceptionally long life (9.5
years in a Trans-Am was the longest, just over 5 years the shortest).
Delcos always have had a sudden death though with little warning--one
reason I keep a battery charger in the garage.  I'm running an Optima
now and really like the high cranking voltage.  Posts on this NG have
indicated that some Optimas wouldn't physically fit in the C4s--make
some measurements before you run to the store and buy one.

I'm not brand fussy as long as the battery is a closed top, "maintenance
free" design--don't want the bad fumes corroding the area.  Interstate
has a great reputation and has good nationwide service--you probably
won't need it though.

PJ

The problem with the Delcos is not that they die any faster than
others, it's that when they do die they don't keep a charge as well.
On the C5, you should only expect the car to sit for 21 days before
having problems, according to the Owner's Manual and experience.  If
the car has to sit longer, get a Battery Tender that works with the
AGM battery.  And if/when it doesn need replacing, consider the
Optima.

www.c5forum.com

After three failed Delco AGM batteries under warranty, I got the message
and my 2001 is now powered by a Wall Mart battery. It was half the cost
of the Delco with more cranking amps and a better warranty.  The best
part is Wall Marts are everywhere and you can get a battery 24/7.