I have been swamped with questions on oils and running a few days behind. 5 -10 questions a day, over 20+ forums is a little hectic ATM.
Cheek out the guide or call castrol techies for a chat, they are more than happy to get your calls.

For lubricant selection guide check out the link below:
http://www.datateck.com.au/lube/castr_au/default.asp?categoryId=3000

Call Castrol tech department directly on [size=10pt]1300 557 998[/size]

Rob.