I've sold a lot of these, and replaced them on my trucks and have pressed them apart... . I can tell you that they have very little grease from the factory... the ones I sold, we had the vendor add additional grease and we specified a full synthetic grease with a high drop point...
On the truck listed below, we pressed one apart to see if the guys posting here we're right, in that you can add additional grease with the ABS sensor removed... We pressed one apart, inspected it, greased it and reinstalled it, oh about 60K miles ago I guess... . but we did verify that if you have the rotor off, pull the ABS sensor and add grease... it will work its way through the housing to both bearings... We added about 3 table spoons, again of a full synthetic grease with a high drop point... .
I hope this helps...