Coolant - how often change?

1) If it's the blue Ethylene Glycol stuff (which it almost certainly will be in a car of that age) then all the bottles I've ever bought have said '2 years protection' or words to that effect.

2) If it still works, then I probably wouldn't bother. It's an ideal opportunity to do it for piece of mind though. And it only costs a few quid so you may as well if you don't know how old the old one is.

EDIT: test the new thermostat before you fit it.. I've had a few duff ones, especially from Halfords. It may need dropping into a pan of boiling water rather than just kettle boiled water poured over it though, as the kettle water's temp will drop fairly quickly to the 'start-to-open' temp, meaning you wrongly think you have a duff...

HTH

I change mine when the hydrometer tells me it needs changing
usually every 2 to 3 years unless you have the long life stuff ?

1) If red, every 5 years, or blue, every 2 years. If it is a mixed metal engine (Alloy head an an iron block for example) I find that flushing the cooling system out also helps quite a bit IME (the last 3 cars I did this on with such engines (Stag, Pug Dturbo, 306 GTi-6 (XU10J4RS engine), and the 106) all had a little fine black sediment come out the DTurbo especially ran cooler afterwards).

Assuming you flush the engine out completely you can go to red which is said to offer better protection (I shall admit my Mondeo's engine was spotless inside when I changed a few hoses) I would stick with blue if you have either a copper cored radiator or heater matrix (I doubt you do in your case.

2) If the car is taking a while to cool down and/or in your opinion stays cool when on a run then I would say yes. Like the others have said, going with a half decent thermostat will also aid matters.

I know it was not the overall contributing factor but on an old Mondeo V6 Auto I had (1600kg with 167BHP) I would see 24MPG around town and I would not say I was dawdling around either. OK, diesels may get more but for what the car was I was mildly impressed!

The above is only what I have found in my experience.