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Gearbox & Diff Oils

14K views 18 replies 7 participants last post by  Sydo  
#1 ·
G'day everyone, I've got some questions regarding oils.

I was at Supercheap Auto today to get diff, gearbox and transfer case oils. I'm not sure whether I've got the right stuff, and other threads I've searched didn't give a clear answer.

For the gearbox and transfer case, I got Penrite semi-synthetic 75W-90. Now the service manual says I should get 75W-90 GL4. The Penrite oil says it it designed for API GL4 and also for GL5. I read somewhere that you definitely shouldn't use GL5 for the gearbox, so is this one OK or not? Also the manual recommends 80W-90 GL4 for the transfer case, is the 75W-90 GL4 OK for this or not?

For the diffs, the manual recommends 80W-90, and the same with LS for the rear. I got Castrol Axle Limited Slip 90. Is this fine to use? And is it ok to use the LS for the front as well as the rear?

Another question: the manual recommends diff, gearbox and transfer case oil changes every 40,000k's. Is this often enough, especially if often driving short distances, and doing regular small and big trips throughout the year?

Finally one other question, do you guys recommend going genuine only, or is it alright to go aftermarket? Are there any kits that make regular servicing cheaper than buying individually? The problem I've got with kits is that I've got a Zd30 airbox, so the air filter is always the wrong one. Cheers, lots of questions but I'm a newbie trying to learn!
 
#2 ·
You need dedicated gearbox oil. 75/90 is no good. Casting a quick eye over the other oils you’ve purchased: looks ok, others will chime in soon no doubt

All my oils are Castrol
Lmx for the gearbox 75 or 80 I think
80/90 for the transfer and front diff
LS 90 for the limited slip prior to installing the Detroit locker and 85/140 in the rear now with the detroit
 
#3 · (Edited)
'00 TD42T manual
Progear 75w90 in the box
Penrite Pro Gear Oil - 75W-90, 2.5 Litre - Supercheap Auto
Transmax Z in the transfer. Gear oil is too thick if you run auto hubs. It can result in the front output shaft turning even when in 2wd due to the added viscosity, this can engage the hubs when not intended. Fine if you have manual hubs.
https://www.castrol.com/en_au/austr.../australia/products/truck-and-bus/automatic-transmission-fluids/transmax-z.html
Syntrax 80w140 fully synthetic in the rear lsd
https://www.castrol.com/en_au/australia/products/cars/axle-and-universal-fluids/syntrax-80w-140.html
80w90 mineral in the front diff (~5ltrs)
https://www.castrol.com/en_au/austr...m/en_au/australia/products/cars/axle-and-universal-fluids/universal-80w-90.html
 
#7 ·
I'd still be nervous about the GL5 compatibility in the gearbox oil. I bought Nulon for mine and there is a synthetic GL5 that the shop were guaranteeing me was OK for GL4 specs as it had been made backwards compatible. The thing is Nulon also have pretty much the same model of oil in a GL4 so I chose to err on the side of caution.
 
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#8 ·
I rang the penrite tech line about the progear GL5 rated synthetic oil.
He assured me it is safe for the synchro rings.
Got it in the Suzuki Swift and the mighty Trol.
Best I've used shift wise in the Trol.
It is also listed as suitable for manual transmissions.
 
#9 ·
The GL4/5 thing hasn't been an issue for years. The sulphur (needed for GL5 to allow diffs to work properly) is now in a form that won't attack the brass syncro rings in the gearbox, but some people refuse to let go of the old ways. "But what if it DOES ruin the gearbox?" I've run Penrite Gear Oil 80W-90 GL5 throughout my driveline since I bought the vehicle. No problems whatsoever.

Depending on where you are located, I'd suggest that the oil you have for the LSD is probably too thin. From the Penrite site.
Mineral, heavy duty, extreme pressure, automotive gear oil. It is designed for use in differentials, both hypoid and limited slip, in light commercials, 4WDs, trucks, construction, earthmoving and agricultural equipment where an SAE 140 grade is required such as in many Nissan 4WD rear differentials.
 
#12 ·
I don’t advise using synthetic oils in an LSD or a Detroit type plate locker. After water contamination the oil becomes sticky and claggy and will lock plates together.
Researching the Detroit I found a few reports of Detroit lockers sticking to the point of braking axles after water contamination with synthetic oils. I’ve also had trouble with wet clutches binding using synthetic oil in motorcycles.
I’d only use mineral no blend oils in the driveline, unless I was racing or some other extreme application