Hi guys, I have just checked my oil level and to my horror there is a milky film on the inside of the filler cap. There is none on the dipstick and the oil is clear and clean. Is because of the cold weather and the fact it was after a short run? Or is this indicative of a head gasket starting to go? The coolant level is fine and shows no sign of contamination at all. It is a 2,8 V6 with only 109000 miles with full history .