Outer Limits 4x4 Board

Have an annoying whine from rear diff or gear box/ transfer at my highway cruise speed, can this be reduced by using another oil????? Dont want to change speed.

Check everything for oil levels. Maybe a wheel bearing . I must say my 93 GQ is real quiet at cruising speeds compared to my last Rover. All you hear is the whirring of the big truck diesel. If everything checks out you could try synthetic oil in boxes and axles. If you have rear Lsd then it is a slipper oil that is specified. It used to be that you put in 80-90 with a little additive but it comes mixed now. I think if you use a fully synthetic diff oil you don`t need anything else in the LSD. A lot of the Rover guys here have had sticky gearchanges which synthetic oils have transformed so they are good. Then again how quiet is a truck drivetrain gonna be?
Alex

It seems to be a known quirk that at about 100km/h under very light acceleration and deceleration their is a slight whine from the rear diff.

This is not present under normal to heavy acceleration or full engine braking.

This gets a few mentions on the patrol forum.