Just a simple question - do I always top-up my antifreeze using Paraflu? In all my previous cars any standard antifreeze could be used so why is Fiat different.

Look for the color, you can top up with the right color anti-freeze, (or distilled water).
There is blue/green anti-freeze, and red/orange anti-freeze, you can't mix them.

check the antifreeze with tester

if lower than it should be just drain some coolant put new in until it meets the tester percentage

it's red in mine which is the 5yr longlife stuff. I usually use Comma G30 xstream antifreeze