I'm a fan of Penrite in general, but I have run 20w50 Shell with no problems. Main reason for the Shell is its dirt cheap. I even ran a 20W60 for a while when I had a really tired motor to help the old jigga along. Again Shell brand. Cheap, cheap!
Due to a recent oil issue with the VZ dunnydore, I've learnt some more about oils. In a nutshell, you will gain more benefit/engine life/better wear from changing out your oil more often than by using a more expensive oil.
As for performance applications, well that's a bit harder, but a mineral oil would be fine. If your not fussed, Shell 20w50. I have no reason to doubt that it will cope just fine.
http://www.shell.com.au/products-serv ... r-oils/helix-hx3/hx3.htmlIf you want to spend some more a Penrite oil of a similar weight is fine
http://www.penriteoil.com.au/products ... d_categ=1&id_viscosity=17Synthetics/semi-synthetics for an A-Series is a waste in my opinion and unnecessary.
On a slightly different, but related issue
Most of the oil manufacturers in Australia run NetLube (or their own version).
Its an online oils application that lists the oils required for your car. Just type into Google NetLube and your preferred brand
Penrite
http://www.datateck.com.au/Lube/PenriteAus/Castrol
http://www.datateck.com.au/lube/castr_au/Plus others