I have a '98 Grand Prix w/ the non supercharged 3800. I'm loosing water, and when i changed the oil (for the first time, just go the car) it was damn near the consistency of water, so i would assume the coolant is leaking internally. I pulled a big grease ball out from under the radiator cap, not sure if its from oil or is this from the dex-cool that was in it?

My question is, which is it most likely, just the intake gasket, or the intake itself?? There is no external leakage around the intake. I do have a leaking radiator which there goes some of the water, but there was definitely alot of water in the oil before i changed it. Any clues would be appreciated.