I little known secret concerning high speed precision bearings.
When they set up same they remove the seals,wash all the original grease out and then pack the bearng with high speed grease .--then believe or not they use compressed air and blow out the excess .Then replace the seals .
It seems to go like this .What ever the small amount the balls can carry,just a slight film ,is all the bearing needs .Any more than that s detrimental .Sounds crazy but that's the way it's done .
Grease as we know it in reality is just oil with a thickening agent .