Junkman
Super Member
nothing strange about this at all. The oil is in there for lubrication of the bearings only. There is so little pressure on the gears themselves, any lubricant will suffice. If this differential were turning the speed of a automobile differential, then the pressures on the gears would be tremendous by comparison, so it would require a different type of lubricant. Today, cars use highly specialized lubricants for each component and many of them cost more per unit than Super UDT.