We took a radiator in last week for a repair and flush and paid for it as such and got it home the next day (1.5 hour round trip) only to find it had obviously not been flushed. You could still see crud through the ports. We proceeded to flush it ourselves with a garden hose to find about 1/2 pound of crud in it that was causing the cooling problem. Didn’t look into it or ask any questions of Tom (radiator tech), just “If you asked us to flush it then it was flushed. Did you stand there and watch? You can always get a little more out of it.” … etc. I suggest you stand clear but if you decide to use them anyway, apparently you need to stand there and watch!