Just to add more confusion - I own a 166 3.2V6, 240bhp. As far as I understand it this is the same engine as in the GTA but with a different plenium chamber and air intake to produce the increased 250bhp. No reason for any different temperature or oil I would think, unless the GTA hooligans are expected to rag it all the time!
The 166 handbook recommends Selenia Racing 10W-60 for the 2.0 T.Spark, Selenia 20K 10W-40 or Selenia Performer 5W-30 for the 2.5, 3.0 & 3.2 V6s.
But I run my 3.2 on Selenia Racing 10W-60. Jamie Porter sells 5 Litres for £36 inc. VAT.

It has to be Italian! Fiat, Lancia & Alfa all my days.
My Alfas - 164 3.0 12v - 156 1.8 SP1 - 164 3.0 24v - 156 SW 1.8 SP3 - 166 3.0 Super - 166 3.2 Ti -
Brera SV JTDM