2007 TDCi - Coolant?

[~Spyne~]

Hi guys, quick/dumb question:
Have noticed the coolant level in my TDCi is rather (very) low and Ford have not topped it up the last few services (it seems). Not sure if they are supposed to, but the car never runs above 60% of the temp gauge, so it doesn't really concern me at the moment.
However, as general interest, would the Nulon Red Long Life Top-Up Coolant be suitable to use for topping up if the car already has the 'stock' red coolant in it from Ford. I know you're not supposed to mix coolants, but had heard this one was 'compatible'?

Also, as the car is coming up to being 5 years old, should Ford be doing a complete flush/refill at the next service?


Cheers guys.