Originally Posted by KelseytheDodgeGirl
What would the 'yellow creamy stuff' signify, If I may ask?
It's emulsification (oil/water mix). The oil cap is the highest point in the system, so it's where stuff collects that isn't burned off. My hemi does this as well. Just wipe it out. You'll get less of it if you let the engine warm up before going anywhere, or ensuring that it actually gets warm. Short trips it generally doesn't get warm enough to burn off the condensation in the oil.