When I was out shopping for a new battery, Costco has a 3-year 100% replacement warranty on their 'Kirkland' batteries, but it was either 12 or maybe 18 months on the Optimas (and they cost twice as much) - If I knew I could get 8-10 years out of an Optima, I would have purchased it, but the short warranty made me question the durability.
Congratulations on getting so much time out of the battery though, that's very impressive!
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