ehh no problem buddy, since ur not losing alot quickly id think itd only be the screw on top for ur coolant resevoir is leaking hot fluid and its evaporating out or the radiator cap is blowing out a little (radiator cap is supposed to be replaced every 2 times u open it up, betcha didnt know that and is supposed to be tested if reused, which noone does). if ur radiator had a hole ud be sure to know about it, cuz ud be losing alot more fluid and ud have a mess to clean up, plus holes get larger pretty quick cuz of the high pressure inside the system, holes in the radiator are easily fixed with acid core soldering compounds available at any acehardware (its the special kind that says "made for radiators") but probably a simpler problem than that even, u dont need to buy a new radiator unless urs is damaged or no longer is sufficient for ur cooling needs (ie ur blowing n2o or have a turbo and ur engine is getting hotter than originally intended). hope that helps u out some buddy