I am trying to find out what everyone is running for gear oil? I did a search and it didn't bring back much for results My FSM says I should be running SAE 90 in the diffs, transmission and transfer case but I haven't found anyplace that carries straight 90w. at least nothing that is GL-5. TSC carries 90w GL-1 straight minerial oil for ford tractors. So I have been running 80w-90 in all the above. anyone see any problems in doing so, or is there a better option besides 80w-90?