I have a 2000 pontiac grand prix gtp with supercharger. I have oil in coolant reservoir, I am not getting the white steam from exhaust pipes. car runs fine. not overheating. I checked the oil dipstick and oil level is fine and it is not milky looking. I am baffled by this, any help would be very helpful

The first solution sounds like that might be the problem if you have trans fluid in the coolant reservoir. If you have oil in the coolant reservoir then this is normally caused when you have a crack in the intake manifold or if the gasket has gone bad. You can either pull the intake manifold off and replace the gasket and check for any cracks in the intake manifold. You may not see the crack. If you do find a crack in the manifold the best thing to do is replace it, change the gasket and then flush out the radiator.

The reason for this is because your trans cooler(which is built into the radiator itself) has failed and burst causing trans fluid to contaminate the cooling system.The fix for this is to remove and replace the radiator with a new one and then flush your cooling system to remove all trans fluid.I hope I could help!!! Any other questions please get back to me and rate me accordingly.