My son has twice let the OEM battery on my 2007 Nissan minvan drain down to the point where it needed to be jump started. (He was watching movies on the DVD system without the engine running.) We also live in South Texas, and the outside temps hover at about 100 degrees pretty much all summer. The van stays in my driveway so it never gets a break from the heat. I am wondering if the battery should be replaced even though I haven't had any problems starting the van yet. Also, what would you all suggest? Optima yellow top or Costco?