Need to change oil on the two but I really don't want to buy and find myself needing a bottle or 2 or even sitting afterwards with sealed bottles taking up space in my cabinet which was bought extra.
I went to my manual but just want to get real world answers also from you guys.
Gearbox 1.1 liter
Diff 600ml

I am planning on buying 3X 500ml bottles for the gearbox.
2X 500ml bottles for the diff.

Nissan says:
* 4-speed gearbox: 1.2 liter
* Japan diff: 0.75 liter
* BW 60 diff: ???
So it seems you will only need 3 liters

Capacities (Datsun 1200 owners manual)



Me? I always had leftover partially used containers on the shelf (I never wrote down how much a 'drain and refill' actually used). But as I recall it never took more than the specified capacity and it may have taken a little less

Also keep in the mind that the steering gearbox uses the same gear oil (GL4) as transmission and differential, but it only needs 0.24 liter. Conversely you could use GL5 in the diff and steering, but the gearbox requires GL4 due to the brass synchros

90W or 80W-90 is good for a bit over 38C degrees temperature. 90W down to 0C, and 80W-90 down to -30C
For very hot climates (40C) use 85W-140

Thanks. Yea, I remember also having partially filled containers left and used it in the chain saw's chain lubricator and wheelbarrow wheel just to get rid of it.

I am planning on cleaning out the steering box also. I just hope sucking it out somehow will work as I don't see a drain plug of some kind. To play safe I will rather use the gearbox's GL4 oil in the steering box.