[Nick]

Thanks guys. Yeah, I noted that it tends to bubble over like a lava flow, gurgling green ooze over the expansion tank. While not elegant, I am at least reassured that this is (somewhat) normal.

So the trick is to over-fill then let it get it its own state of natural harmony? How low should it go - seems to drop a bit down the tank (when warm) but them come back up (when cold).

Being Nervous Nelly over this, but an overheating engine in an old car in a hot country is not a pretty scenario...

Actually its at BVO right now being pressure tested - just to make 100% sure there's no small leaks or hairline cracks, etc.