Running hot

[Henry99]

Hi all, I am wondering if anyone here can help sort out a problem.
What the trouble is that when city driving the temp guage goes right up close to the Hot mark, the low fan cuts in at 2 marks back from hot, its runs about half way on a freeway but as soon as i get into the suburbs, stop, start, the temp guage gets awfull close to the Hot mark which of course makes me nervous, it doesn't boil up on me but it is winter in my neck of the woods now and not looking forward to the hotter days to come.
The things I have done so far [ there is no coolant loss.]

changed the thermostat [seems to be working fine as the top radiator hose warms up as the motor warms ].
changed the temp sender & checked wiring.
changed the temp sensor unit [ the one that signals to the ecu]
checked both fan relays.
flushed out coolant & replaced [no air in system, bled it properly]
water pump is only 12 months old and is working fine.
checked all over the radiator once warm [ no cold spots ]

If there is anything else I should check, i would be most gratefull for any replies, this is really driven me nuts.

Faulty temp guage perhaps ? I really don't know.
I phoned a GMH dealership & was told that this model car runs a bit hot on the gauge, nothing to worry about, but the thing is, I have owned this car from new and it never done this until about 2 months ago, the most the temp guage would read would be half way even on a very hot day.

would appreciate any advise.
thanks

[Johnp33]

If you have an inferred temp gauge you can test the gauge against the actual tempature. also you can test the coolant tempature coming back from the radiator, it should be at least 170. Check you have proper air flow, threw the radiator, and the shroud is complete. If you can tell us what the vehicle is it would be easier to diagnose. Check your rad cap, if it does not hold pressure, all kinds of symptoms are possible.

[Henry99]

Thanks John for your reply, I haven't got a inferred temp gauge but will chase one up to check the coolant temps, the radiator cap is about 3 years old so I will get another one this afternoon and try that, thanks.
The air flow is good threw the radiator and the shroud is complete.
I am an Aussie so you might not be familar with our cars, but anyway its a V6 ecotec motor [ GMH - Holden ] 12 year old vehicle.

again thanks very much for your help.