I just recently purchased an 02 X5 3.0i with 86,000 miles as a daily driver so the M5 wont have to get up for daily duty. It is sienna red on beige with sport premium,and winter package. I love the car but have noticed since it started getting very cold here in Reno NV that there is a yellow sludge buildup on the oil cap and I have tried to go for about an hour drive at freeway speeds but it still wont go away. I haven't replaced the CCV or any related hoses either. Why wont it go away!?