Worm clamp size and Coolant compatability
 

These go from the main supply and return pipes (metal), become the rubber hoses, then connect to the main engine supply and, on the other side, the thermostat. These are the hoses that are right underneath the front engine mount.

I need to buy 4 worm clamps for them and just need an idea of size. I'm thinking they are ~30mm external but if anyone can give me some comfort before I place the order...

Also, can anyone confirm that pentosin g12 coolant is compatible with Porsche OEM coolant? I've got 5 liters of Pentosin, so I figure I'll supplement with a single gallon of OEM coolant as long as it's compatible. Can't imagine it's not....