follow-up... I went to dealer and they had a record from previous owner. They pro--rated at 50% off so we were at $57. By the time tax, disposal fee, some $1 fee and shop charge(BS I installed it) it was $68 out the door for oem Nissan battery with 2 yr return and 84 month life. They said they use interstate batteries:tup:

yah sounds about right. no need for expensive batteries.

That battery sold by Amazon is a Optima Batteries 8020-164. So, is this battery Optima Battery 9020-164 a new version..... https://www.summitracing.com/parts/u...san/model/370z

Nissan battery
 

Looks to me like a typo on Summit's site. Optima's site specs the 8020-164 for the Z. The other number doesn't exist on their site.

Bought my Z in March 2011, still the original battery. I do keep it on a tender when not in use...I am sure it will need replacing in the near future..will go with Optima which I have used on many cars..like the idea of no acid weeping out.

I bought my '09 new in Sept. 2009. Replaced the battery in July 2013 as a preventive maintenance measure since my experience tells me that batteries usually fail around 48 months with little to no warning. It was an Interstate brand with a 60 month warranty. Guess what ? It failed without warning a couple of weeks ago after 38 months of service. I bought another, and even with the pro-rating of the remaining warranty it still cost me $100. Good thing the battery was dead when I tried to start it to go to work in the morning and I wasn't stranded somewhere. My insurance covers roadside assistance and a guy was there to give me a jump in 20 minutes. I figured a 60 month battery should be good for at least 48 worry free months but it failed and I always made sure it was topped up with distilled water. The Optima batteries look nice but don't have a good reputation. Buy a good battery and swap it between 36-48 months no matter what the warranty and you'll have peace of mind.