Recently purchased a truck for the future shop build, got it on the road and it’s almost ready, few minor maintenance things that need to be taken care of. One of the lift axle hubs is a bit low on oil, so some needs to be added, I was at autozone and they told me that gear and hub oil are different and I need to use the correct oil, I’m just topping off and don’t know what’s in there, what oil would be best to use? The rear diffs I want to check and add if low, same thing not sure what kind of oil is in there, what would be best to replace it with? Same thing with the trans, it’s got a 8ll. Better to check and add then run them dry!
When in doubt, change it out. Obviously might cost a little, but it's probably due anyway. 80W-90 in the hubs, synthetic 75W-90 in the diffs, and synthetic 50W in the trans. Some guys run the 50W in their hubs as well, 80W-90 is cheap and plentiful.
75x90 synthetic in the hubs-steer, drop and trailer. 75x90 synthetic in the rear drives. 50 wt synthetic in the transmission. Your in a cold climate run synthetics easier on it in real cold conditions.