Doesn't make much sense does it. We got 8 years out of our original Buick battery. The Interstate lasted 5. Still not too bad but what is in the OEM batteries that aren't in the replacements? My original PT Cruiser battery only lasted 3 years but the car got stored and the battery discharged totally a few times. The Diehard replacement lasted 7 years but I pit the maintainer charger on it while it sat in the winter. That seems to make a difference. It seems that once the battery goes completely dead it shortens the life.
