The Optima's carry a 3-year replacement, with 3-year pro-rate. They have a total warranty of 6-years.
http://www.optimabatteries.com/publi...anty_info.html
We had one die in the car after about 1.5 years. Went to Sears and got a brand new one for free. Not sure exactly how old the one in my truck is, but I would say 5-6 years old. Never had a problem with it.