That would be the head gasket, unless it is ATF, engine oil will be brown and cruddy. ATF (from the cooler in the radiator) is reddish and does not produce the cruddy, brown residue. Hope it's the latter.
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.