C'mon all you experts. Quit showing off your ignorance. This is NOT snake oil! We're dealing with real chemistry today. A popular battery additive sold in the 60s, 70s, and 80s (when you could unscrew those caps on top of your battery) was called VX-6. It worked. A battery that could no longer hold a charge could be treated with VX-6 and it became rechargeable again.
The ingredients were secret but was known to contain cadmium. Over time, the plates on a lead-acid battery would become sulfated and unable to take a charge. VX-6 could partially reverse the sulfation. Those who used it and charged their battery saw instant improvement. Some claimed the battery would become functional for another two years.
"If this product actually worked then one should ask themselves why the battery manufacturers are not dribbling a bit of this stuff into every battery they make."
They do, sort of. There are rechargeable nickel-cadmium batteries. For automotive considerations the battery additive is only useful to a lead-acid battery after it has become sulfated, not when it is healthy.
I've heard that battery additives of this type are preferred by those who use the marine deep-discharge batteries. I'm not a boater so I have no experience with this usage.
I used to maintain my car's old-style battery by checking its specific gravity and adding distilled water when necessary. No more. Today's car batteries tend to be permanently sealed. You can't simply add stuff any more. But, guys, don't knock this stuff. It really works. The issue is between whether it is worth using or simply replacing a dying battery now rather than shortly down the road.