Sorry, as I was walking up from the lab I was reminded that some plastics will have 'oily' type residues when new. The reason for this is that the molds used for these will have release agent which are not a million miles different from your trim dressings. This is even more the case with tyres and you often find that the new tyre 'look' is a result of residual mold release agent adhering to the tyre.