So I bought this new radiator (I won't name the manufacturer publicly) but there up there with the best of them. Payed a considerable amount of money for it. I've noticed my reserve tank slowly emptying and today I decided to have a look in to it. It turns out it's leaking from the thread where the nipple joins the radiator. So I think to myself I'll just pull it off and put some sealing agent on, well it's threaded now and yes I was trying to be careful. Now I'm not blaming manufacturer as it is partly my fault but this could have been easily averted by either sealing it from factory or welding it in.

Also curious if this Leaking problem has happen to any one else.