Open your oil filler cap and put your finger in there and swipe around and see if the oil seems "milky" or has a white hue to it. If so you have signs of having a blown headgasket as Samurai said. Also check the top of your radiator as the very thin stock radiator tends to have the seal on the top go out and you may be leaking out anti-freeze at a slow rate from the top of the radiator.
