Millers 5w-30 fully synthetic in my '04 3.0.
You can look on Millers Oil or Castrol Oil's website & they have an 'oil finder'.
You may have a heat issue in Oz with daytime temperatures 'slightly' higher than us european chaps!
You'll probably find several different thoughts on here, we all have our own favourites!
Same as 'which filter', some people swear about Wix some swear on Mann (think they maybe the same company now) I've got a Wix oil filter in mine [as did previous owner for the past 4 services] so again, different people different thoughts!
Hope this helps.