I bought my car in March earlier this year so haven't really had much use of it in cold temperatures. Over the last week (with lower temps) I've noticed that If I drive carefully off turbo I can get to work 14 miles and the car still hasn't got to temperature (and the heater is aired). If I drive with the turbo spinning the car gets to temp and the heater gets warm. Only problem then though is if I drive steady again the heater goes cooler (also if stationery in traffic). Does this sound normal or could the thermostat by on it's way out? Are there any easy ways of checking?