Which diff oil for ARB locker?

[pradgo Lurker Find all posts View Profile Close pradgo]

I need to change rear diff oil in a 2008 Prado with an ARB rear locker. In N Qld and thinking 85W-140, GL-5. ARB used to say avoid LSD additives, but it looks like that recommendation has been dropped. SAE J2360 specs look way better than GL-5 so I'd like to find an oil with J2360 certification.

Can you recommend any readily available gear oils, and/or have experience with 75W-90 vs 85W-140? Any clues on how sensitive ARB lockers are to gear oil viscosity? I got the Prado used and don't know what's in it now, but the diff oil still looks good.

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

Diff oil comes out looking good even if it’s been in there for a while. I’d personally stick to the specs for the car’s rear diff as opposed to what ARB recommend because you’d prefer to look after the diff. Plus how often do you use your rear locker compared to how much your rear diff is worked in every day use. If you’re maybe concerned about FNQ temps breaking down the diff oil quicker, just change it 20,000km before the specified intervals. Don’t go mucking around with different viscosities for it. The specified SAE90 rear diff oil is plenty thick enough and won’t thin out during 34 plus degree temps. It’ll do the job just fine.