73 Lt95 Gearbox Oil

[Garfy]

Hi all , having scoured all the Info on this and came to the conclusion that i should use VMX 80 in the TC and GB I then did .
My beast is a 73 that i've Renovated (body wise ) and when i surprisingly got my Roadworthy last week (she's been sitting for 6 months ) decided after her first long run (200k ) decided to drop the oils in the Diffs / Swivels and
Gearbox / Transfer . The oil in the LT 95 look a bit Green but thick . It now seems a lot more noisy / clattery / rattly . I added moreys with both fills and have checked the levels and is ok . Sorry to ramble or should I put 20/50 in which is what i imagine was in before .
Thanks Garfy

[Blknight.aus]

they usually run a 15/30 or a 15/40 depending on whats in the engine..........

they do alright on anything from ATF through to 15/45 Ive never run anything thicker in them.

if its rattley, its probabley bearings or the suzi pushing it....

[Garfy]

I blew my work van up on tuesday so maybe a bit paronoid as I have to use my barely ready Weekend Rangie as my work beast .
She just seems alot more rattly after i changed the oil .

[Range Blitzer]

I converted my '82 Rangie from auto to LT95 last christmas and filled the freshly cleaned out box with VMX80. Wasn't reco'ed just tidied up. Is a bit noisy but hasn't missed a beat. Seems to go ok for me!
Robert.

[PhilipA]

Mine always went OK on 20-50 oil as that is what is recommended.
VMX 80 is a single grade so may be thicker when cold, and the Moreys worries me a bit.
The oil pump shaft can shear on a cold morning if the oil is too thick, and that can make the box noisier and rattly. Hmmmmm.
Just keep the transfer with the same stuff as they exchange bodily fluids.

I once put Penrite 20-60 in and that was OK until it warmed then I couldnt change gear.
Regards Philip A

[Garfy]

Thanks Blk Night and Range Blitzer , have blown up a Bullet Proof Toyota Hiace van this week and have to resort to the beast for my livelyhood so am a bit concerned . But whatever , I saved her from the crusher , she might save me !
Meanwhile
Anyone got a Donk for a 93 Hiace 2.4 Petrol (Cash Waiting )
Thanks Gareth

[Garfy]

Philip A
Am expecting the worst (as that's the only way ) so if i've done the damage its already done . Maybe i'll bung in some half decent 20/50 and hope for the best .
Thanks Garfy

[rovercare]

Thanks Blk Night and Range Blitzer , have blown up a Bullet Proof Toyota Hiace van this week and have to resort to the beast for my livelyhood so am a bit concerned . But whatever , I saved her from the crusher , she might save me !
Meanwhile
Anyone got a Donk for a 93 Hiace 2.4 Petrol (Cash Waiting )
Thanks Gareth

Just sold a 22R:(

[Garfy]

It never rains !

[djam1]

I found VMX 80 too thin for my newly reco LT95 it changed better but was noisier I reverted back to synthetic engine oil to be honest.
The other thing VMX 80 is very thin and it leaked profusely despite only just being reconditioned.

[PhilipA]

I just had a look at the SAE 100c (cst) of both gear 80 and 20-50.

The 80 is about the same as a straight 20 engine oil with a 100C cst of 7.

So it is much thinner at 100c than 20-50 engine oil, so that is why it rattles.

Have a look below. The smaller the number the thinner.
SAE J306 English (http://www.widman.biz/Seleccion/Viscosidad/SAE_J306/SAE_J306_English/sae_j306_english.html)

Regards Philip A

[Garfy]

Will try a quality 20/50 in her as a i believe thats what would of been in there before .
Thanks Guys

[110county]

HPR30 mineral, HPR15 synthetic-------can either of these be used in an LT95 box, and which is better? and why? Thanks for any advice. 110county

[PhilipA]

Many years ago I tried HPR30 in my 81 RRC which is 60 when hot.

When it got hot I couldn't change gear.

Stick with a 50 grade when hot. It doesn't matter whether it it is 10,15, or 20 when cold . Ie the first W number.
Regards Philip A

[Meccles]

Just filled mine up with Castrol GTX 20W-50W which is Castrols recommendation. Figure cant go too wrong with that.

[Mercguy]

Oil threads are a very topical thing - by that I am inferring that it doesn't matter what is technically correct, there are always conflicting opinions as to what to use.

For myself, I always stick with the manufacturers recommended products, unless there is a specific requirement to change.

I went through several varieties / brands with the getrag transmission on the 16v, and found that the 'best' fluid was actually the genuine bottled MB ATF, which had a quite unique specification for the specific 717.404 (GL275E) manual.

However, after investigating and using several (quite expensive) different brands, I ended up replacing the MB spec'd ATF with Neo Synthetics Hi-vis, which is effectively a 7wt gear oil, full synth, but with an inordinate amount of technology 'inside'.

Without going into too much detail, and starting a war/riot/argument there is a very good reason for using a 'gear' oil in a manual transmission as opposed to engine oil... And that is 'shear'.

A gear oil has much higher shear strength, and this literally translates into the 'film' of oil that covers the gear components and remains 'stuck' if you will...
Motorcycles with wet clutches and gearboxes that share the same oil as the engine also have a much higher quality shear strength than your average engine oil.
It all has to do with the intended function of the oil itself.

So in that respect, if you were wanting the extreme film strength and high molecular shear strengths, then you would use one of the more expensive motorcycle synthetic oils - motul 8100 for example, as your 'gearbox' oil.
But, you still have a change interval to adhere to, and in that respect, a dedicated gear oil has the superior friction modifiers (which do not have to suffer exposure to combustion byproducts) higher film strengths and consequently a slightly higher base viscosity.
Yes, you will need to choose a suitable product which provides the same ideal viscosity as the original specification of oil. So if that is a 20 weight or 50 weight SAE viscosity, then you should choose a product that matches this, as the design of the internal components is such that an excessively thin or overly viscous oil may contribute to starvation of lubrication or damage.

In the case of the borg warner transfer case, I run the hi-vis neo on that as well now, after a year of careful observation in the 16v gearbox.

My actual opinion on the subject is fairly straightforward. Where specified, the synthetic ATF's are OK, as are the super expensive dedicated synthetic gear oils. However I would never run an engine oil in a gearbox (for reasons previously stated) even if the change intervals were the same as the engine oil - there just isn't the same amount of protection afforded in an application which is designed to create a shear characteristic, because gearboxes are not combustion engines, and vice versa.

If you must run an engine oil in a gearbox, then at least do yourself a favour and look to the high quality full ester synthetic 4 stroke motorcycle oils, and change the oil as frequently as you change it in your engine - if you want to afford the best levels of protection.

It's just a consumable, but you can save a lot of money by choosing wisely with a high quality synthetic gear oil designed for the application (and the change intervals can be extended by a huge margin because of the extremely high specification)

Just some food for thought.

[Davo]

There's a good reason for not using gear oil in the LT95 - the little plastic oil pump that apparently likes to break when asked to pump cold 80w-90.

I was using cheap 20w-50 in mine - which was brand new - and then changed to HPR30, which is what's in the engine. The box has been much quieter since. The synchromesh requires double-declutching when cold with either oil, though.

[Tank]

We used Castrol VMX-80 as recommended by LR and the original owner Stage 1 had been driven round Australia and my Son drove it from Kalgoorlie to here with no problems.
Whatever oil you use it needs to be GL4. Most gear oils are GL5 which is not compatible with non-ferrous parts in gearbox, this oil is very thin so will not harm the pump, check out Castrol web-site, Regards Frank.

[PhilipA]

My actual opinion on the subject is fairly straightforward. Where specified, the synthetic ATF's are OK, as are the super expensive dedicated synthetic gear oils. However I would never run an engine oil in a gearbox (for reasons previously stated)

Your theory is quite valid and in many cases I have used gear oils in gearboxes.

BUT the question remains-

Why did Land Rover recommend to use engine oil in the LT95?

Even back then they would have access to Oil company specific formulations as they seem to now quote the most exotic oils for their gearboxes.

Could it be that their testing indicated that 20W-50 engine oil was ideal for an LT95?

I can recall that I had an LT95 in Saudi that someone had used 80W-90 gear oil and the pump was sheared and the thrust washers destroyed.

Perhaps the width of viscosity difference between hot and cold is incompatible with high sheer strength in gear oils as you rarely see a large difference in viscosity . Although Nulon do make an 85W-140, which I mix with 80W-90 for my transfer case.

Regards Philip A

[Blknight.aus]

Your theory is quite valid and in many cases I have used gear oils in gearboxes.

BUT the question remains-

Why did Land Rover recommend to use engine oil in the LT95?



it was LR's first pressure lube fed gearbox. I recall reading somewhere that it was originally triald on hydraulic oils but with a shorter service interval it was found that the engine oil of the day was up to the task and having a single oil for multiple components made it easier to maintain in the field.

Gear oil was quickly eliminated initially due to the loss of flow rate through the pump strainer and then because of the loading it put on the pump that either chewed out the teeth or the square drive of the pump.

Im halfway tempted to trial the box on someting like a hyspin 48 hyd oil but I dont have a run up bench or the gauges to monitor the pressures and flow rates in the box.

[Meccles]

So, back to what to put in, 20W-50 GTX engine oil works just fine. As it did for 12 years when I used it previously :) Yes other oils may work, but bang for buck hard to go past this:):)
If anyone here has worked on mini's with common sump engine/gearbox, that also runs engine oil...

[Homestar]

So, back to what to put in, 20W-50 GTX engine oil works just fine. As it did for 12 years when I used it previously :) Yes other oils may work, but bang for buck hard to go past this:):)
If anyone here has worked on mini's with common sump engine/gearbox, that also runs engine oil...

Agreed, I use this in then engine and bix on mine - cheap, and you only have to carry one too up container. ;)

[Mercguy]

it was LR's first pressure lube fed gearbox. I recall reading somewhere that it was originally triald on hydraulic oils but with a shorter service interval it was found that the engine oil of the day was up to the task and having a single oil for multiple components made it easier to maintain in the field.

Gear oil was quickly eliminated initially due to the loss of flow rate through the pump strainer and then because of the loading it put on the pump that either chewed out the teeth or the square drive of the pump.

Im halfway tempted to trial the box on someting like a hyspin 48 hyd oil but I dont have a run up bench or the gauges to monitor the pressures and flow rates in the box.

That would pretty much be it in a nutshell - i.e. serviceablity and availability versus cost.

But don't forget, vehicle manufacturers do not want their products to last forever...

So the use of an engine oil in a gearbox was purely a commercial decision, which found itself substantiated by a design fault in the pump, which meant that it couldn't handle high-viscosity hypoid gear oils.

So consequently, there should be nothing wrong with a dedicated low-viscosity gear oil, provided it remained stable throughout the operating temp range (which really is not hard to do, when you consider the original oil was mineral 20-50...)

The biggest issue I see, is that so many people do not adhere to the service intervals for gearbox and diff oils.... why? because they don't get dirty looking like engine oil does, so they think it's still OK.

My absolute worst case change interval is every 12 months on diffs. I do 15K intervals on all my auto gearboxes (which is about half the recommended 'extreme hard use' guideline) and since owning the RRC, swivels and engine get 5000km services, trans has had one service interval, and will be due in 6000km time for it's next, BW has had 2 changes (every 5,000) but now it has Neo in it, I will simply monitor it. I have been assured it can go the lifetime of the transfer case without worry, but I'll get it analysed at 30,000 for peace of mind.

Insofar as using mineral hydraulic oils- hyspin46 would work, but you would also have to consider service intervals, and perhaps initially have the oil analysed after 100hrs, to see if there was any breakdown. Like all things 'untested', it's only proven to work after it has been 'tested' and tested in the real world (i.e. until failure). My only question is whether hyspin actually has the correct properties for pressure fed gear applications, and not specifically hydraulic ram applications

It would be OK if someone had a spare LT95 and a willingness to test.

If it was my LT, and I wanted to remain loyal to the engine oil recommendation, I'd be looking at 10-40 synthetic motorcycle oil and checking it at the first drain interval, to see if the oil was suffering breakdown.

If I wasn't concerned about adhereing to spec, then something like Castrol Syntrans 50E would be my choice if I wanted a straight grade oil.

Oil companies are great at providing PDF BS, so one really needs to look past the press advertorial junk and look deep into the specs and independednt lab test results if they wish to be certain of facts.

Given that the current modern 20-50 engine oils are totally different to the prehistoric 20-50 oils once used and which were once suitable, I would have my doubts about using a modern engine oil. Especially when they are high in surfactants, low in anti-friction compounds, and full of marketing BS.

but if I didn't care, I'd just buy the cheapest crap out there, chuck it in and hope it worked, and if it didn't and the box lunched all it's gears, then oh well, just get another gearbox......

[Meccles]

Interesting post with many valid observations. Will have to think about it and digest. Hadn't really thought that long and hard about oil for gearbox as LT95 has been such a reliable unit in past with GTX. It seemed a no brainer to keep using it. But, it was 18 years ago when I last used GTX in an LT95 and as you correctly point out, oils ain't oils anymore.

[Bearman]

It's been proved that the 15/40 engine oils are a recommended and excellent choice for these boxes so why not use it? Castrol Syntrans appears to be another that works well especially with a tight box. I wouldn't bother using hydraulic or atf oils. I have stretched box oil changes out to 50k without any problems.

[Homestar]

I change mine every 2 engine services - that seems to coincide with Castrol GTX coming on special at Autobarn. :D

[Meccles]

I ran this question past Bearman. He said any good quality 20W-50 oil. But was very specific, said not to use any ATF/ Hydraulic type oils. I figure as he rebuilds them he should know.

[Meccles]

This was response from Penrite Tech department:

Range Rover, 3.5 Litre V8 Eng., 4-Spd. Man./ Auto., 4x4 (1974-1984)

Manual gearbox > On our website we actually suggest a mineral oil equivalent to a straight 30 (but really SAE 20W-60)--- HPR 30. Service fill is listed at 2.6L, but a dry fill will be more, of course.

From the product information:

...............HPR 30 is suitable for use in motorcycles with wet clutch assemblies and is also suitable for use in gearboxes requiring a SAE 30 non friction modified engine oil. It is suitable for use in vehicles with a combined engine / transmission application such as BMC Minis, especially those used in competition conditions...............


Regards,
Alan Jeffery
Technical Support

This looks pretty decent oil for both engine and trans so might have to give it a go.

[Mick_Marsh]

The service book recommends SAE 20W/50 API SE oil (Penrite HPR 30). The ADF documentation recommends SAE 40 (Penrite HPR 40).

[PhilipA]

As I posted earlier, I tried HPR 30 and couldn't change gear when the transmission became hot in a 77RRC.
This was about 16 years ago so maybe the oil has changed but I think not.

My trans was overhauled prior to this but I think it was all the transfer case with new output gear , new intermediate shims and new diff shims, but AFAIK the actual gearbox was not touched and had several 100KKs on it.
Regards Philip A

[Davo]

Thinking of this, I tried straight gear changes in mine, (I usually double-declutch out of habit), and it worked well while hot, with HPR30. So maybe it was your gearbox after all?