I recently took off my front diff cover sealed it with rtf gasket and filled it and before a hundred miles the oil was low. (I couldn't feel it with my finger)

After I got the cover off today I started thinking maybe I should've just added some more oil as I couldn't tell it had been leaking

Also the hub assy needs replaced. Could one be affecting the other?

Can the oil burn up like engine oil causing the level to go down?
Any ideas are appreciated

Black 205 f150 4.6

 

I've seen this on Jeep front differentials when the seals are bad.
The oil would work its way into the axle tubes.

 

thanks do you mean the pinion seals or the diffcover seal

 

Neither. The seals the were supposed to keep the differential oil from entering the axle tubes.