Mine threw out codes for misfires on all cylinders, O2 sensor limits, O2 adaptation limits. I got a small oil leak to the valve cover gasket too and another (bigger) to one of the hoses coming to the OS, however once again I'm driving in hot climate so I didn't experienced some major issues described by some owners living in very cold areas.
Depending of your mileage and how old your X is, replacing the OS is one of the most useful preventive maintenance...

thanks for the help.

thanks for your input sfcl!

from the picture i upoaded, do i also need to get #1 too or just hoses?

BMW makes a $450 kit that wraps these pipes, it plugs into the wiring harness and keeps the oil separator warm. My car has a bad separator too, I could here oil squirting from behind the engine onto the block.

from the picture i upoaded, do i also need to get #1 too or just hoses?

#1 is the OS, you need to replace it AND the hoses, common cause of oil and air leaks. To be complete on the subject of air leaks on these motors, I wouldn't replace the OS and its hoses without replacing also the intake boot and the various vaccum lines. They are not expensive and you can take advantage of the OS replacement job to be sure that everything is ok while you are at it...

I had my dealer replace the OS, hoses and dipstick tube last January when it all froze up and blew out the valve cover gasket. Would it be unusual to have a problem again this year even though I've gotten new parts installed? Last weekend she had some rough idle early in the morning after the vehicle sat out overnight. I checked the dipstick and under the oil cap and there was a small amount of the teltale milky oil. I'm wondering if I need to replace the OS again or can I just take it apart and clean it out? Would cleaning it out just delay the inevitable?

Yes, cleaning it out is the appropriate action if you have replaced it a year ago. The buildup of condensate is only inevitable if you don't drive it long enough to get it hot, at least hot enough to boil off the condensation.

i was just told by a professional that the oil separator for e53(os and its hoses) is same as e46. pls, advise.