I had a counterman at the autoparts store look up what Land Rover
said goes into it.

Looked like 70W-90W synthetic. So, that's what I pumped into it.
Valvoline in a grey bottle.
Synthetic seems to by nature leak out of transfer cases and engines more easily.

 

You should have followed my Major service list for fluids, 85/140 works much better, and cuts wear on all the moving parts over 75/90.

As for the inspection plate, just remove and reseal it, it is a quick 1/2 hour job.

 

I agree with mike your vehicle has some wear and tear on it now opposed to when new. 85/140 is going to protect and provide better liberation use that + white shepherd.