Im telling you again my friend. The northeast and everywhere with freezing temperatures is susceptable to this oil seperator pandemic. Poor engineering has led many to change to a newer designed seperator(if they even make one), or the need to install electric heaters for them. Ive taken my X5 off the road from november to april for this exact problem.

Wow! An SAV you can't drive in the winter or during really cold weather! Sounds really crazy but I can see your reasoning.

Has anyone had any luck insulating the valve, I would think some properly used foam pipe insulation from homedepot would work for some of you.

I have some foam insulation tubing and aluminum tape...I'll give it a try when I do my intake manifold swap.

I HIGHLY doubt its the oil pump. I know in the late 90 540/740 motors there were instances where the oilpump bolts came loose and would cause a rattle. Removing the oil pan in the X5 is a bitch in itself, and an expensive guess if you mechanic is wrong. I'd start simply w/ the OSV and all the lines running to it before you let him turn your wallet and X5 into an expensive project on your dime.