I know BT has a lot of petrolheads who seem to know their stuff so I thought I'd ask your advice on a problem I've been having lately. I own a 2010 Astra 1.6 petrol, and recently I have been having an issue where the engine temp will start rising, and keep rising if I don't pull over and stop. Now it only does this if a) the engine has been running for quite some time (i.e. on long journeys or lots of little trips around town) AND b) I am in slow moving or stationary traffic. I could be driving down the motorway at 90mph all day and it will be fine, the problem only arises when I come to a slow crawl or stop for around 5-10 minutes or more. Also, I have discovered that putting the heater on full blast will keep it running at its normal stable temperature and even reduce the temperature from an overheating state. Obviously that is not really ideal in the current weather we've been having though. I've checked all the obvious things - the engine coolant is brimmed and it's only just had a full MOT and service with no faults found. At first the symptoms lead me to believe it was just a dodgy radiator fan but I've checked it a few times when the engine has started to overheat and the fan is running fine. Is there anything else that it might be that I can check? I don't really want to put it back in the garage and be charged an arm and a leg for labour costs if it's a simple fix. Even if it's just an idea of what the problem might be since if it could be serious I'll have to get it looked at straight away.