best oil for gearbox

Gearbox needs a 75/85 to avoid the cold shift problem. Castrol VMX-M or Valvoline Duragear 75/85 are good. Many others are not.

Diffs: its OK to put the LS90 into the front diff as well as the rear.

Scott,
I use a Royal Purple synthetic oil in my gearbox and transfer case, it's certainly helped my cold shift problem on both my old GQ and my newer GU, the gearbox also runs a bit cooler when I'm towing.

Scott,

Use Shell XGO 75/90 in g'box and t'case, seems okay. Cold shifting isn't a real problem where we are!

Use Shell Diff Oil in rear diff(marked for LSD), and Spirax 85/140 in front diffs. Sometimes use Diff Oil in front as well.

Some of the synthetics are supposed to be good.

Hooroo...

Hi Scott. I use Redline full synthetic MT90, it has viscosity of a 15w40 but gear tooth load rating of sae 140. I had a cold shift prob before using 74w90 the Redline has fixed this. Be warned it is expensive!
Regards Ken.

Howdy Scott

Gearbox Shell XGO 75w/90 transfer case use XGO 75w/90. Now if the rear diff is LSD use Shell lim slip 90. Now if the rear diff isnt LSD u can use XGO75w/90 same as the front diff or Spirax A or AX 80w/90.
As I only use Shell oils on all my machine's ranging from 100 series LC, SWB Maverick and my new kawasaki zx9r and had no probs.

Rossco

Hi Scott,

I just put Castrol VMX-M in both mine and dad's deisel 80 series. Both have done about 230,000k's. Mine I just did it as part of regular servicing and noticed straight away how silky smooth the change is now compared to before. Mentioned it to dad who was always saying his was a @*(#^$(*&# to get into 2nd when cold and I drove his and it grated every time I went up or down the gears into 3rd. Now it is slick and smooth again, he can't believe it.

It is available at Repco or Supercheap in 4 litres which is the exact quantity needed for our gearbox and transfer cases. I used a plastic masterfood sauce bottle with a bit of hose on it as a filling bottle. Only about 250ml bottle, so the 500ml bottle is better as you don't have to refill as often.

Here is a link to Castrol's VMX-M

As for the diff, I have a non LSD in the back and have fitted airlockers front and rear. ARB recommend a good LSD oil in both front and back with their Airlockers fitted, so YES, you can use same oil in fornt even though it's not an LSD.