Pontiac Repair: car help, intake manifold gasket, coolant level

Question
When i got home from work I noticed when idealing that the car was making a wined up noise with very solf almost knocking noise to it. The noise sounded the same even when the RPMS were increased. I pulled the oil cap out and noticed a pasty clay texture to it that had a meduim brown color to it . You could not see the color of the inside of the cap because of how thick the residue was on it, nor did it feel smooth. The oil was not old, because i just recently did a oil change on it. All you could see covering the inside of the oil cap was a pasty clay texture to it that was meduim brown colored. It did not appear to be normal oil, even if it was getting to a point where the oil needed to be change it still did not look like regular oil. What does this mean?

Answer
Hi Joel:
what type of car is this? take a look at the coolant level in the radiator or in the over flow tank. check it when it's sat cold overnight. any kind of oil discoloration uaullay is because coolant is mixing with the oil. It will have a white/tan tint to it. If that were the case depending on the engine it could be from an intake manifold gasket leaking or a head gasket leaking.