[Lynn Eades]

Arie,No oil in the bearings. Just use a modern wheel bearing grease for packing the bearings. Don't fill the cavity. Maybe a smear around the inside if you want.
The inner hub seal keeps the grease in and the dirt out.
The outer hub seal stops the diff oil mixing with the grease.
Back in the day, I think a bit of extra grease was pumped into the bearings at servicing time. Todays grease is so much better. How often are front wheel bearings in a (rwd) car repacked? Nearly never done.