Yes, interesting this. Despite all the threads which indicate that ACEA C3 5w40 oil is the correct grade oil for the TwinAir and the 1.2 etc, it would seem there are 'two versions' of the owners manual floating about, one stating 0.9 TwinAir 65HP 85HP and 105HP SAE 0W30 ACEA C2 Fiat 9.55535-GS1 only, and the other 5w40 ACEA C3, classification 9.55535-S2.
So then, who's going to stick their head above the parapet and say without all shadow of a doubt which is the correct oil to use? Clearly I knew what went in the 1.2, and despite what I can see in my own owners manual, the doubters have made me start to doubt what I see before my eyes, so even I am having difficulties about what the TwinAir uses! I'm more than happy to call a Fiat dealership, but I wonder how many different answers I'll get

So technical gurus who actually work at a dealership and service these cars all the time, speak up!