From what I've been reading in posts here, I'd say that the stuff isn't working. I once looked into it for my older RWD R12 Volvo and found a place that sells a sealer kit that's so expensive that for me, I'm better off just systematically replacing whatever AC part fails AND yes, on older Volvos too, something's always leaking freon from somewhere. I don't think there's been one year that I didn't have to at least add some freon that leaked out over the winter and I've replaced every part so far BUT the evap (the one thing that rarely ever leaked on older pre-850 Volvos).