Those other oil's mentioned above are all good stuff. They have the same or better spec's than the figures I quoted you. If you don't need specialist stuff, just get the Valvoline, Castrol or Shell stuff that meets those numbers.
4 litres will cost $20 to $28, and with the 1.5litres you have left, change the diff oil at the same time, it usually needs just 1 litre.
Mitch.