? oil manual gear box

[Daniel]

Hi,

After reading many threads about oil grade to use in gearbox I'm still confused.
So what do I need for a 5 speed m/t in my 2000 Nubira?

User manual state for SAE 80W.
But no indication if GL4 or GL5?
Does this gear box have non-ferrous synchromesh?

Thanks,

Daniel