I brought my X5 to Classic BMW today, the problem they found was
three crank case vent hoses split up.

they replaced three hoses and oil return, oil separa, several clamps, I have no idea about what are those parts. I guess those problems were caused by my driving too much locally.

the total charge was $520, I paid $230, the rest is covered by the CPO and ESC. not bad.

good thing was they loan me a BMW even I am not eligible for it, because my X5 is over 50k now, and it was not purchased from this dealer.