Initial thought about low temp, as i had the same, is that the thermostat is stuck open. Mine always ran quite cool and never could get much heat into the car in the winter. I changed the thermostat (used stock 195f) and it was great after that, ran at 84c when driving.

For the overheating, i've done a tonne of research (not saying i'm an expert by any means of course) and overheating / running hot tends to be a relative term and depends on the definition of 'hot'. I've noticed that people who have gotten 3rd gens after having a 1st or 2nd gens say that their 3rd gen runs hot, because they were running their previous cars cool (some going for as low as 165f thermostats. The stock thermostat on a 3rd gen is 195f, so car should be sitting at around 200 - 220f. Especially for fuel injection and emissions, they were designed to run 'hot'. Mine ran 84c while driving, creeping up a bit in traffic to the 90's, then the fan kicks in at 108c (225f) and brings it down to 98c (210f) (Canadian car, so temp gauge was in c). Cross checking this against the GM factory manual, the numbers match to spec so while it initially seems like it may be running hot, it fits what GM designed them to run at. Running lower temps isn't always a good thing - i had a horrible fuel smell all the time, as the engine was running too cool and the ECU didn't go into closed loop mode, so was adding extra fuel to try and warm up and also meant that fuel wasn't being fully burned.

Another thing worth noting with running cool / no thermostat, is that it means the radiator is always moving fluid, so it doesn't act as a reservoir of cool water when it's needed. Having a stat, especially oe temp, means the engine warms up to temp quicker (as water is not circulating through the rad) and allows the radiator to hold cooler coolant during driving, as it will close off during normal driving, allowing the coolant to cool down nicely.

Hope that helps a bit?

Glad it helped!

I've seen them go for about £7-10 on ebay uk from sellers such as u.s automotive and john wolfe racing. I think they come with gasket too. At that price though, i would buy from rockauto, as it's £9.15 delivered from the U.S (£7.32 for shipping, £2.42 for the stat. You could go for a cheaper stat as they start at £0.72!). At that point, i would add in a few extra's to make the most out of shipping i.e. rad cap, a few gaskets etc. That's what i always do with parts - it usually costs about the same in the UK due to overseas shipping being expensive, but as soon as you add an extra item you start to save a noticable amount.

Thanks for the vote of confidence Rockinfox!

How did you get on with it Old_Git, any progress or waiting on parts to arrive? Hopefully it's all sorted and you're able to enjoy the car.

Snow? Oh dear, that always puts a stop to things. Are you up North? The cold is starting to set in