Eight years out of your batteries is a lot. I suggest changing them unless you want to try to milk a few more months out of them, and change them at a campground or along the road when they fail. I would change them now at your convenience. Sears Diehard use to be a good battery but I don't know about them now. I use Interstate and am well pleased. An Interstate company store will change out the batteries for you. Most auto parts stores will also change them out for you. I would stay away from Walmart batteries.