Rear wheel bearing lubrication

Hi All, getting ready to put new gears in my 9 inch. While I've got the axles out, I will be replacing the rear wheel bearings also. When I pulled the axles, I found the same milkshakey stuff on the axle shafts as was in the pumpkin, so clearly the diff fluid can move up the axle tubes.

But the wheel bearings I got (Timken) are packed with grease, and the instructions also say to make sure they are packed with grease. But I'm pretty sure that grease and oil aren't supposed to mix. So I guess the question is twofold.

1 - Are the rear wheel bearings lubricated by grease, or by the diff oil?
2 - If by grease, what keeps it separate? That collar towards the inside of the axle? It didn't really look "watertight" to me.

Thanks!

1. Yes, lubed by the diff oil. I was told to grease them when you replace them or are in there. My understanding is that it gives it lube until the diff oil lubes it.

2. Nothing separates it. It must mix, been working a long time.

Thanks Dane, I guess I'll go with that. It certainly didn't feel right to install them with no grease. Wonder how long it takes for the grease to all wash out into the oil.

Pete Whitstone wrote

Thanks Dane, I guess I'll go with that. It certainly didn't feel right to install them with no grease. Wonder how long it takes for the grease to all wash out into the oil.

Good and interesting question.

I was thinking about that too after I posted here. I assume when it gets warmed up the two mix better.