When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
That would depend since you dont use it much it could still be good. You should go check it at a reputable store. They usually check it for free so they can sell you a new one. If you decide to change make sure it has at least the same amperage as the oem and that it is COMPLETELY SEALED.
Your 2000 should NOT have an AGM battery. I would (and did) replace it. Use an AGM or Gell battery.
Don't take a chance, any regular lead-acid battery can leak. I had a DELCO leak in a new Pontiac Bonneville. In your C5 if it leaks, the computer and the wiring harness can be toast ! They are located directly under the battery.
I replaced my DELCO with a Champion XLT (AGM Battery) size/number DT35/CHXDT35 made by Exide. Got it at SAMS Club for $90-95. It has 690 CCA, 850 CA, a 36 month free replacement and free jump-start, and a 108 month limited warranty.