1.5 Liter of 75W140 GL5 Differential oil (LiquiMoly) and 2x new filler caps for the rear differential. I didnt have the correct hex key, but a T70 torx also works. Will be doing this again in the near future, so all the old oil is replaced with new oil.
I used a big syringe (150ml), which actually worked out very well. I will always recommend using new plugs whenever you notice that the plugs look old.
Draining the old rear differential oil