I have a 2003 focus st170 and I have the same thing happening but I just thought that when in traffic or town driving it sits constant at half way the same asthe engine temp but when I get on a good sstraight road the engine temp starts to drop and oil temp goes down near the bottom but I just took it that it was just the cool air blowing through the engine.So I never thought of it as a problem.If u find out there is a problem post it up so I no aswell.