On my 1.9 5 pot the guage reads about 2 and a half bar when fully warmed at idle then goes off scale when driven (which I assume is ok).
However when I put the heater fan on full speed the oil temp guage rises and pressure guages drop considerabley. I guess there is a voltage drop somewhere but it did freak me out last week when I put the fan on to cool me down a bit then panicked cos I though the engine was about to overheat/run out of oil
