I have used 6v Optima batteries for almost 5 years with no problems. They are relatively expensive but have proven to be cheaper per year compared to the 6v cheap batteries I used to buy.
I let my Optimas sit in the trucks all winter (in northern NY) and the engines turn right over and start up every Spring (with no charging).
Someone who supposedly used to sell Optimas has posted that they are unreliable. That is the opposite of my experiences (and the experiences of at least 5 other owners of 6v Chevy & GMC trucks).
