tonydan..that grinding noise may be your belts re-aligning.. Our cars do that when they've been sitting in the cold... Its most likely not related to your seperator... Mine makes a grinding start when on super cold days..I've had the seperator replaced and taken care of... That noise is my belts warming up and trying to align properly...It does that because of the cold temps outside. After a few seconds the noise goes away..Also the noise does not happen unless the car has been left in the cold and sitting for several hours...

Furthermore, let this be noted. Oil seperators can fail at any temperature. Summer or Winter. They seem to fail more often in the winter because conditions are more favorable for failure, but that doesn't mean they won't fail in the summer too. The part itself is not a lifetime part, it will fail after 70k miles or so..Its not a question of if, its a question of when...