Make sure it's a welded radiator and not an epoxied one! Also, I've used a lot of aluminum radiators and have had the best cooling with the two core units with the cores at least 1/2" thick.. I put a Norther radiator in the Merc, Steve idled around all afternoon Thursday with the temp in the mid 80's. Temp stayed at 180-186 with a 185 stat!!! Also, as with any radiator, it takes a good shroud to make them cool correctly...