Thread: R380, transfer case and Diff synthetic oils

Penrite only list TRANS GEAR 75W-80 (Semi Syn.) For gearbox. Cheers

Castrol do a full synthetic oil, i use it in my r380. Although the price is about $ 40 per lt

Castrol Syntrans 75w-85 | Castrol Australia | Castrol Manual Transmission Fluids | Castrol™ Australia | Car - Motor Oil & Lubricants | Castrol Australia | Products | Castrol Australia | Castrol™ Engine Oil & Lubricants - Castrol™ Australia

Thanks mate. Saving on labour makes it easy to use the best fluids. Did you notice any differences with the synthetic in there? Cheers

I see that RAVE required API GL5 whereas the Syntrans does API GL3 and 4. So no good for transfer case. Ok for gearbox. Cheers

Originally Posted by ozscott

Thanks mate. Saving on labour makes it easy to use the best fluids. Did you notice any differences with the synthetic in there? Cheers

The car had an ashcroft hd rear bearing box fitted just before i purchased it. It has had syntrans since then, although once in karratha i couldn't get any so tried the next one down and the shift quality suffered, so i changed back after 20k

R380 fluids, and just my opinion FWIW.

Castrol Syntrans 75W-85.
Used it for a very long time.

Penrite Pro gear 75W-85
Never used it but rated by those that have.
IMO it suits Australia better than ATF or a 75W-80, and I've had Syntrans thin out at high ambient/high loads to the point that shifting has deteriorated and bearing rattle be quite pronounced.

Motul Gear 300 75W-90
My favourite in the R380, and thanks to chemical trickery it's thinner at 0*C than Syntrans.
Gear 300 can be used in the T/case too, I use it in the Deefer with the Maxi low range gears and ATB centre diff, and it can be used in the diffs if you can get past the sticker shock.
It has an exceptional viscosity index, meaning it resists thinning past 100*C better than any 75W-90 I've seen.
The oil analyst I use reckons Motul is over-rated, but he has a little bit of antipathy towards the French.

Castrol Syntrax Universal 7w5-90 is a very good fluid that can be used in the t/case and diffs, but has gone up in price considerably.

I've never used Penrite's Pro Gear oils but am about to fill the t/case in the D2 with Pro Gear 75W-90, purely as it was a good price in relation to Castrol syn in Alice Springs.

Originally Posted by rick130

R380 fluids, and just my opinion FWIW.

Castrol Syntrans 75W-85.
Used it for a very long time.

Penrite Pro gear 75W-85
Never used it but rated by those that have.
IMO it suits Australia better than ATF or a 75W-80, and I've had Syntrans thin out at high ambient/high loads to the point that shifting has deteriorated and bearing rattle be quite pronounced.

Motul Gear 300 75W-90
My favourite in the R380, and thanks to chemical trickery it's thinner at 0*C than Syntrans.
Gear 300 can be used in the T/case too, I use it in the Deefer with the Maxi low range gears and ATB centre diff, and it can be used in the diffs if you can get past the sticker shock.
It has an exceptional viscosity index, meaning it resists thinning past 100*C better than any 75W-90 I've seen.
The oil analyst I use reckons Motul is over-rated, but he has a little bit of antipathy towards the French.

Castrol Syntrax Universal 7w5-90 is a very good fluid that can be used in the t/case and diffs, but has gone up in price considerably.

I've never used Penrite's Pro Gear oils but am about to fill the t/case in the D2 with Pro Gear 75W-90, purely as it was a good price in relation to Castrol syn in Alice Springs.

Rick, this motul oil, would it be good to use in my isuzu msa 5 speed? Currently been using vmx80 (15-40 is specified). Also i have an atb in my tcase so may use it there as well

Originally Posted by Vern

Rick, this motul oil, would it be good to use in my isuzu msa 5 speed? Currently been using vmx80 (15-40 is specified). Also i have an atb in my tcase so may use it there as well

Damien, I used it in the t/case purely as it doesn't have any LSD additives, so suits the ATB well and can handle the high temps our t/cases run at, and an ATB (they rely on friction to work) will only increase the running temp.

Syntrax Universal would work well there too, basically any transaxle fluid would suit.

In pure (kinematic) viscosity terms an xW-40 engine oil is roughly equivalent to an xW-90 gear oil.
Most 15W-40's and Gear 300 are around 14.5 cSt@100*C.
VMX-80 is only around 10cSt@100*C, it's a 75W-80 trans fluid so a bit thinner than a 15W-40 engine oil at high temps.