So I have a 2003 S500, my front struts have been replaced but now there is an issue with the rears.. In addition the valve block has also been replaced and the lines leading into and out of the valve block have been checked over, tightened, and re-sealed by the dealer mechanic. So the issue now is that I live in Minnesota and when it dips below about 10 degrees F the rear drivers side strut completely goes down. The colder it is below that approximate temperature the quicker it goes down. I have witnessed it go from regular height to completely sunk in 3 hours before. I went to the dealer for them to check it out, however the mechanic from the dealer that worked on my car was not there, I trust him the most because he had the same car as me and he was the only one to finally figure out my valve block issue. None the less, someone else checked over my car and very quickly said my left rear strut needs replacing. They quoted a price that of course was dealer price and so I took it to the shop that replaced my front struts. However they said they could not find a leak anywhere in the strut, they even tried to look at it from the top view, behind the rear seats, and none of their senors, instruments, etc showed any sign of leakage from the strut. If it is lets say 35 degrees F the car sits perfectly for days and does not drop, however as soon as it gets near the 0 degrees the left rear completely sinks as if half the wheel is inside the wheel well. The right rear may possibly drop A millimeter, but it isnt noticeable if at all. Has anyone dealt with this kind of issue. I am not sure if possibly the valve block has a bad seal with the line to the left rear strut or maybe a line somewhere is leaking? Right after I start the car, the car rises no problem, although once i had to start it twice for it too rise. The problem is that for the next few months the temeps are be similar so I am not sure what to change or just leave it be if no one can figure out what it is. Thanks for any suggestions, recommendations, ideas, etc.