I've recently replaced both my batt.'s w/ new 850 cca Motorcrafts. My old batt.'s were still going strong at 5.5 yrs. old but didn't want to press my luck. I know some of you use desulphators and wanted to know what kind would be the best to use? Some claim that you can double the life. Hard to believe, but it would be great. I'd really like to get schooled on these desulphators, and get one that I'm not wasting my money on.