r380 oil guru's question.

**dromader driver** · 12th August 2019, 05:02 PM

Gear box oil is up for a change and found recommended oil hard to find. In comparing traditional gearbox oil with Syntrans seems the viscosity at various temps seem to be very similar in viscosity. Wondering if I am reading this correctly as considering using penrite outback hardened 80w90 which seems to be very similar in viscosity and not an issue with brass etc. Viscosity may be a little thicker when hot

80w90
TYPICAL DATA
Colour Blue
Density at 15°C, kg/L 0.894
Viscosity, Kinematic, cSt at 40°C 152
Viscosity, Kinematic, cSt at 100°C 15
Viscosity Index 99
Viscosity, Brookfield at -26°C 53,800
Phosphorus, Mass % 0.06

Syntrans
Viscosity, Kinematic100°C ASTM D445 mm²/s 11.9
Viscosity, Kinematic 40°C ASTM D445 mm²/s 64.4
Viscosity, Brookfield @ - 40°C (75W)
DIN 51398 mPa.s (cP) 18000
Pour Point DIN-ISO 3016 °C -45
Density DIN EN ISO
12185
g/ml 0.837

Have I missed something??

**rick130** · 13th August 2019, 07:37 AM

Totally different viscosities when cold!
Look at the viscosity and VII.

152 vs 64@40°!
I'm in the phone atm but if we plugged those numbers into a viscosity calculator the 80w-90 would be like treacle at close to zero, and probably bugger the 'box as it possibly wouldn't flow through the galleries fast enough to lube the bearings

That 80w-90 would be bloody awful, don't skimp on using a decent fluid in that 'box.

Plenty of posts and threads on here on what is used and what works well.

**86mud** · 13th August 2019, 09:44 AM

I have just changed the oil in my R380. I run Penrite in everything else in my Defender, apart from the R380 which I have always used Castrol Syntrans 75W-85 full synthetic.

The R380 was due for a change so I decided to try the Penrite Progear 75W-85.

Now I am unable to select second when the box is cold. So this weekend I will be swapping back to Castrol Syntrans 75W-85. It's not cheap - at about $33 for 1 litre at Repco. But it's worth it in my opinion, My box shifts super smooth at all temperatures using the Castrol Syn Trans.

**dromader driver** · 13th August 2019, 12:44 PM

Originally Posted by 86mud

I have just changed the oil in my R380. I run Penrite in everything else in my Defender, apart from the R380 which I have always used Castrol Syntrans 75W-85 full synthetic.

The R380 was due for a change so I decided to try the Penrite Progear 75W-85.

Now I am unable to select second when the box is cold. So this weekend I will be swapping back to Castrol Syntrans 75W-85. It's not cheap - at about $33 for 1 litre at Repco. But it's worth it in my opinion, My box shifts super smooth at all temperatures using the Castrol Syn Trans.

Thanks, exactly what I was after

**101RRS** · 13th August 2019, 01:12 PM

When I had my D1 I had Syn trans in it.

Ok on -5 Canberra winter mornings and also Ok on +40 Canberra Summer afternoons.

Just go with SynTrans - never saw it as high as $33 a litre but then I buy oils when on special.

**Markf** · 13th August 2019, 03:13 PM

Originally Posted by 86mud

I have just changed the oil in my R380. I run Penrite in everything else in my Defender, apart from the R380 which I have always used Castrol Syntrans 75W-85 full synthetic.

The R380 was due for a change so I decided to try the Penrite Progear 75W-85.

Now I am unable to select second when the box is cold. So this weekend I will be swapping back to Castrol Syntrans 75W-85. It's not cheap - at about $33 for 1 litre at Repco. But it's worth it in my opinion, My box shifts super smooth at all temperatures using the Castrol Syn Trans.

X2

**87County** · 13th August 2019, 10:26 PM

I know that Syntrans is expen$ive - but much, much longer oil change intervals are recommended.

**djam1** · 14th August 2019, 04:49 AM

The only problem with Syntrans is it shears quite badly within 20000 kms
Requiring a change interval of no more than 20000
On the advice of Rick I used motul 300 an absolute bitch to change when it’s cold but magic once it warms up

**rick130** · 14th August 2019, 07:53 AM

Originally Posted by djam1

The only problem with Syntrans is it shears quite badly within 20000 kms
Requiring a change interval of no more than 20000
On the advice of Rick I used motul 300 an absolute bitch to change when it’s cold but magic once it warms up

Duane, that just goes to show how idiosyncratic the R380 is as I found Gear 300 better when cold than Syntrans!
Unless Motul have reformulated in the last four years, which could've happened?

It definitely survives longer than Syntrans, with a much better change in high ambient/high load conditions

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