Optima's have a life of 4 to 5 years if your lucky. Optima knows this and they stopped the prorated exchange. The warrantee is now 3 year period with a full replacement anytime during the 3 year period. They have an internal space of about 1" over the cells in the battery. The lead out of the cells, 8 or 9 cell ends are about 7/8" wide and .025 thick cell ends that connect the cells and connect to the battery terminals in this area. This area has a small vent hole allowing air into this space and over a period of time the 8 or 9 cell ends are etched away in this atmosphere and get very thin. When they get real thin a big starter load blows the weak thin lead apart like a fuse. This is why they normally have a sudden death, not a weaking condition. Some other make batteries have a check valve instead of a vent acting only to release gas if it gets a little pressure and not letting air in. If Optima had a valve I think life would be a little longer. I still like the Optima and buy them knowing any time I get over 3 1/2 years is a plus. I know some will post they have one for 6 years but this is not the norm. G.M.