Usually these additive packages are either nothing more than a supplement to the additives already in your motor oil or they really are something that's slick as snot but will eat through your block once it begins to decay from heat.
I'm surprised they're still in business the FTC was after their ass in a major way a year or so ago.
BTW, it's their (possessive). They're over there working on their car.
And yes... now I'm in a bad mood... went to get back to work on a fiberglass project and found that I'd bought three cans of expired resin a month ago... great, three liters of worthless purple jelly. UGH!