I too run oil bath hubs and like them. With that said they are not bullet proof. My practice is to inspect my hubs at every stop including taking their temp with a laser gun (inexpensive and well worth it tool). Four years ago on a trip back from the WCVI I had stopped for fuel and done my check. All four hubs showed the proper amount of oil and the temp on all four hubs was only slightly above ambient air temp and the same for all hubs. A good check in my book. Eight miles later I was on the side of the road with a melted spindle and small fire to put out.
Clearly somehow within 8 miles the offending hub had "dumped its oil". Our best guess on the post mortum sifting through the melted parts is that some road debris kicked up and hit the viewing port on the hub hard enough to allow the oil to escape. Obviously with no oil things heat up very,very,quickly . . . .too quickly to really catch it. Obviously in a grease packed hub that won't happen . . . .but of course as we all know other things can happen with a grease packed hub.
I believe that my situation was a fluke but it goes to show that nothing is bullet proof. I still run and prefer oil bathtubs. I think that the ability to see the lubricant is a huge plus.
The way to cure the problem you describe is pack your bearings with a compatible grease to the gear oil(easy) then you have the best of both worlds-if you lose your oil-your grease will save you. Incidentally I have travelled 5 to 6000 km every year for the last 7 years with oil bath and never once dumped oil-I have sprayed it once due to a cap not being tight enough-but no damage done-just tightened it. I do carry spare caps. Tight Lines.
Changed the oil in the hubs today.....EZ loader dealer said the plastic caps come off pretty easy with a strap wrench.
Put my strap wrench on.......applied a little bit of pressure....the left cap broke in two.
Back up to the dealer to get the aluminum ones (bought a pair)....these are tougher than the plastic ones....no fear of breaking.
I was also told to use some Loctite sealer on the little filler nut when I put it back in ...which I did.
Paid 22 bucks total for the 2 new caps.........
View attachment 11725