Basically my drive to work is about 10 mins , the car is usually just getting warmed up by the time I arrive . My question is , is that substance just moisture mixing with oil ( only seems to happen when its cold out , I don't remember it happening when it warms up ) it looks like a thick yellow sludge . I run mobile 1 15k protection full synthetic in it. This is basically just my woork car and dd. I do notice also that when coming to a stop the heat doesn't seem to be as hot as when I'm driving and the idle is up. Car has 88k on it and no cels nothing at all has been running great ( is running great !) I changed oil at like 82-83k miles and the level is still good everything looks ok aside from that yellow substance , so any insight would be great thanks !