ve ss rear diff oil??

Hi guys.

I found the knocking that come from rear diff when I put the gear in.

So first thing I wanna try is change the diff oil and add some additive?

but cannot find GL-5 75w-85 from anywhere near my town.

Iv been Supercheap, Autobarn etc...but they dont sell it as they said its lifetime oil WTF ??

Also been Holden but was told by staff that they only sell them in barrel not in bottle...lol


So is there any alternative oil that I can use for my 07 VE SSV with manual transmission?

Also what additive exactly do I need for my car?



Thank you