I bought a quart of Macks engine flush, from Napa, and used it. Heres what i noticed, as i poured it into crankcase, some crud that built up under the oil fill cap, in the crankcase, dissolved away immiedialy! Seemed to be strong potent stuff!! ANyone else use this item? It dissolved crud on contact, where seafoam never did sucha thing, or gunk engine flush for that matter. It advertises, it cleans out ring packs, valves, oil channles, ect.