Do the set, they rarely fail only one at a time -- a bad one gets hot, melts the grease, and the crud from the bad one migates into the good one, you know what happens next.

Iv'e been told to fill the hub with grease after greasing the bearings, leaving the hole in the middle completely free, with only a dab in the cap. The grease in the hub and cap are only there to re-grease the bearings if they get hot -- the stuff in there will spin out, but the "extra" will also melt a bit and run in to replace it.

If you use a knife to fill the hub, it takes just about 60gr of grease.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!