I was on the fence about buying more ARX for a while. I was using it for a long time, then the last 4-5 oil changes didn't see any. But a pending intake manifold gasket replacement (preventative maintenance, knock on wood) on my 99 Buick LeSabre prompted me to buy it again to assist in cleaning up any residuals. So I broke down and ordered 3 more bottles to use in my and my fiancee's cars. I figure it's going to be a short change interval in my car after changing the gaskets, might as well clean things up a bit!