ah I see. You know now that I think of it the situation with radiators is even more dire: it is difficult to tell exactly how a radiator will perform from a picture. Some oil coolers are rather poor performers, but some do quite well. Some heatercores work substantially better than others also (edge soldered ones). A picture really isn't suitable; need internal volume, surface area, some standard testing. I have been talking to a German block maker (
http://watercool.de/), and they are really pushing for a standard test procedure and methodology whereby performance curves could be generated that all makers would use and that were comparable between manufacturers (and between hardware sites). Sounds like an absolute nightmare to me (I doubt you could get US hardware sites to all agree on the weight of a waterblock much less its performance). Maybe we will see some spillover of this concept to the US though.