[Aufenbahn]

My car makes a groaning sound from the PS when it's down around 5deg outside. I think its because the fluid thickens up at low temp. So if what you put in is really thick it might act the same way.

BTW If it's the pump that's leaking go to Rennbay and buy their rebuild kit - they have a video shows you how to install... Really not too hard to do.