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Gearbox oils


northernchris
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The synchro are designed for a lower viscosity lubricant. In addition there is a pump inside the gearbox that is not designed for high viscosity lubes.

MTF IS a real gear oil. So is ATF...... Auto gearboxes have gears too......

Most modern manual gearboxes use low viscosity lubricants.

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The synchro are designed for a lower viscosity lubricant. In addition there is a pump inside the gearbox that is not designed for high viscosity lubes.

MTF IS a real gear oil. So is ATF...... Auto gearboxes have gears too......

Most modern manual gearboxes use low viscosity lubricants.

Really auto boxes have gears!!!!! come on really,sorry but i have seen more gearboxes than you have had hot dinners.Atf compared to real gear oil is carp,in the £48k wrc boxes i build we use pumps for lube aswell as for hydraulic purposes for controling diffs and activ roll control etc etc and we use 15/50 weight oil!!!!!!

autos have gears doh???? really

:lol:

Edited by northernchris
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What do you call "real gear oil" then?

I have just put about £45 worth (landed cost here) of Difflock's much vaunted MT75 extremely fancy full set of bells and whistles included manual gearbox oil in my R380 about a week ago and frankly there doesn't seem to be much difference to either Land Rover's MTF94, or the ATF (Castrol TQF then later on Castrol Dexron III) that I used to use in the old 90. The cold gearchange is noticeably better (first 100 yards on a cold morning), but when hot (after a bit of use offroad in low range for example), if anything it is slightly worse, and to be honest it is not really that much different to the gearbox in the old one running ATF.

A chap I know used to use ATF in his 90 gearbox, changed to MTF and then changed back again because he reckoned the gearchange was better with the bog standard ATF.

Hmmm £4.80 for ATF or £45 for fancy stuff ... I wonder what I'll use next time round :rolleyes:

Bog standard ATF might not last as long but at 1/10 of the price you can afford to change it every service ... expensive stuff might be needed in fancy gearboxes but as I don't run a gearbox costing nearly as much as my house, I think ordinary oil will probably do me OK :)

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Really auto boxes have gears!!!!! come on really,sorry but i have seen more gearboxes than you have had hot dinners.Atf compared to real gear oil is carp,in the £48k wrc boxes i build we use pumps for lube aswell as for hydraulic purposes for controling diffs and activ roll control etc etc and we use 15/50 weight oil!!!!!!

autos have gears doh???? really

:lol:

The story as I understand it (maybe Mr. Ashcroft can add details) is that the pump it not a very robust design and can be broken from the use of high viscosity lubes in cold weather.

Trust me that the synchros are designed for the low viscosity. The gearbox will not shift in cold weather period with "real gear oil" as you put it. If you put in 75W-90 or similar have fun trying to shift below 10 C.

There are lots of quality "gear oils" that have low viscosity and are designed specifically for manual transmissions.

Here is a list of some.

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The story as I understand it (maybe Mr. Ashcroft can add details) is that the pump it not a very robust design and can be broken from the use of high viscosity lubes in cold weather.

Trust me that the synchros are designed for the low viscosity. The gearbox will not shift in cold weather period with "real gear oil" as you put it. If you put in 75W-90 or similar have fun trying to shift below 10 C.

There are lots of quality "gear oils" that have low viscosity and are designed specifically for manual transmissions.

Here is a list of some.

[/quote

It sounds like to me that the pump is the limiting factor in the box,i the reason i talked about putting another type of oil in the box is to help with shock loading etc.

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If I remember correctly, the LT95 and LT85 have a pump gear/spindle made from a fibre material, which can break if an oil with a too-high viscosity is used in cold conditions. However Mal Story from maxi-drive told me the only instances of this he was aware of (in Australia) was a few early LT95s that were filled with 80W90 gear oil and then used in snowy conditions (yes we do get snow in OZ).

AFAIK the LT77 has a metal (brass?) gear. So presumably the LT77S and then R380 would have retained this gear. This is unlikely to be broken by oil that is too viscous.

From what I have heard, the low viscosity oil is required to provide adequate lubrication to all parts of the box, and also decent shifting in cold weather. In my experience with my (reconditioned) LT85, when I originally bought it it was filled with 80W90, and when I first got in it it was barely possible to make the 1-2 change. Replacing the oil with Castrol VMX80 (similar to MTF94) made a huge difference.

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  • 7 months later...

In the owners manual it specifies 15W40 for the LT85 box (compared to MTF for LT77).

I was a little surprised, as its the first time ive put motor oil in a gearbox, so i had to double check.

But having drained the ATF that was in there & put in the 15W40, it it much much smoother & quieter.

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Autoboxes have gears - epicyclics! The LT85 used engine oil as the lubricant (but separate from), as did Minis (shared with engine) - the BMC/Rover type not the modern thing!

LT77 and R380 internal oilways for the bearings are not wide enough to cope with cold "gear oil". My mate had a 1 liter Suzuki SJ which if i didn't keep the idle high enough in cold weather would stall cos of the drag of the EP90 in the main and transfer boxes...

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Luke, the clicky link doesn't work, it just throws up

We encountered a problem. The reason reported was:

Access Denied.

This is not necessarily an error. If you feel this is an error then it could be something as simple as your browser not being set to accept cookies. If you feel this error is a problem with the server then please contact landroverowner@emap.com and let us know what exactly went wrong so it can be fixed as soon as possible. Otherwise, please use your back button to return to the previous page.

:rolleyes:

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What oil is everyone putting in their gearboxes??? Has anyone put 75/90 in the R380 box?

Regards Chris

Castrol Syntrans 75w85 full synthetic in my LT77S.

Castrol SAF-XA 80w140 full synthetic in everything else - transfer box, front & rear axles and swivels.

Paul :)

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Really auto boxes have gears!!!!! come on really,sorry but i have seen more gearboxes than you have had hot dinners.Atf compared to real gear oil is carp,in the £48k wrc boxes i build we use pumps for lube aswell as for hydraulic purposes for controling diffs and activ roll control etc etc and we use 15/50 weight oil!!!!!!

autos have gears doh???? really

:lol:

I thought Xtrac recommended Neo RHD in their 'boxes ? what 15/50 oil are you using ?

A normal car type gearbox doesn't need the EP additives that a hypoid diff does, it just doesn't see that level of loading, although the blokes that blend fluids reckon it will shear it pretty quickly if the blender has used any VII's in it (and this is why MTF94 should be changed more frequently than something like Redline MTL or Castrol Syntrans)

Generally an LSD fluid just won't work on a synchro 'box. The friction modifiers used to reduce clutch plate chatter generally makes the synchros innefective, although i've used Neo 75/90 HD successfully in a Peugeot and it improved the shifting markedly. None of this matters a rats in a competition dog box where you can use diff fluid with impunity.

As to low viscosity fluids needed for synchro engagement, it's possibly the most important charcteristic below -5* yet viscosity is only one factor that contributes to synchro engagement. The fluids co-efficient of friction is also vital and this is apparently the main characteristic specific manual trans fluids like Redfline MTL and MT90 (75W90), MTF94, Syntrans, et al are trying to get right.

A couple of blokes here are using Castrol Syntrax (I think this is SAF-XO in Europe, it's a PAO/ester GL5 75w/90 non-LSD fluid) in the R380 without a prob. (so far) Approx 14.5 cSt @ 100*C.

I found straight Syntrans or MTL thinning out too much in summer here, (rattly, harder/notchier shifting) and so have a 60/40 MTL/MT90 brew that seems to have solved that problem.

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I did quite a lot of digging for my NV4500 5 spd manual trans from the States. Over there, they recommend ONLY Syntorq LT SAE 75W-85, API GL -4 manual transmission lubricant - due to the combination of wear, synchros and shifting ease. In fact I got some shipped with my gearbox, but for the future, I'll be using the options stated below.

They don't sell Syntorq LT in the UK, but my investigations with Castrol threw up the following (snippets, so don't expect logical sense):

"...Castrol TAF-X 75W-90 GL-4 gear

oil is made in the U.K. and sold only in Europe. ... the equivalent

in the U.S. is Syntorq LT. Having said that, Syntorq LT SAE 75W-85, API

GL -4 is a premium high performance, synthetic gear lubricant for

synchronized manual transmissions. The all new "clean slate" approach

enables Syntorq LT to provide consistent performance and durability

under the most severe operating conditions due to its unique polymer

free formula. It has been designed primarily as a problem solving gear

lubricant for manual transmissions to provide reduced gearshift effort

at low temperatures. Syntorq LT is available through General Motors

(Part #12346190) and Chrysler (Part #4637579) dealerships. Please

contact your local dealership."

And:

The main difference being that the TAF-X is a little more viscous when

it's hot so you'll get a slightly thicker oil film - so I'd say that

would be my first choice from a protection point of view. The SMX-S (available at Halfords) is

also a fully synthetic, GL4 - but a 75W-85 - we use the SMX mainly for

automotive applications ( Ford gearboxes mainly ).

TAF-X - Castrol Classic Oils in Cambridge - 01954 231668 - try them

Maybe some of those are worth investigation? Al.

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Al, you might find that Syntrans would make a good replacement for Syntorq LT, although as you mention, Castrol make a few manual trans fluids in the 75W-85 range.

Syntrans is mainly aimed at ZF and Volvo light and heavy commercial transmissions in Europe and has a Volvo Heavy Vehicles pt #.

Here it's recommended as an all round heavy duty manual trans fluid (eg R380 when towing, various Mitsubishi's, etc) and competition (synchro) manual trans fluid, as well as heavy commercial 'boxes requiring a 75W-85 GL4 fluid, eg Volvo.

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Thanks - though for info, the only time I've seen it referred to regarding the NV4500 is to say: "Always use Syntorq, NOT Syntrans"...!

Which is why I contacted Castrol and sorted out the best possible equivalent.

Good thinking though!

Al. :)

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Castrol Syntrans 75w85 full synthetic in my LT77S.

Castrol SAF-XA 80w140 full synthetic in everything else - transfer box, front & rear axles and swivels.

Paul :)

If you are using expensive fully synthetic and off-roading I think you are wasting your hard earned dosh!

Much better to change all oils at 12,000 mile intervals or sooner if contaminated with water. Whether expensive fully synthetic or cheap(er) ATF if it's mixed with water it's the same cr*p!

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If you are using expensive fully synthetic and off-roading I think you are wasting your hard earned dosh!

Much better to change all oils at 12,000 mile intervals or sooner if contaminated with water. Whether expensive fully synthetic or cheap(er) ATF if it's mixed with water it's the same cr*p!

doesn't rain here...... :P

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I thought the EP additives in gear oil corroded the yellow metal parts in the LT77 and R380 boxes.

reactive sulphur is hardly used anymore, you'd be hard pressed to find a GL5/hypoid diff oil that uses it.

GL-5; Specified for hypoid gear service but with shock loads and severe service operation. Usually meets Mil-L-2105D and in most cases, is the multipurpose automotive gear oil. Most 75W90 to 75W140 grades meet the GL-5 classification. This grade has a high level of Extreme-Pressure additives that could be mildly corrosive to nonferrous parts, such as brass, bronze and aluminum parts. Most of the modern GL-5 lubes contain metal deactivators that prevents attacks by the extreme-pressure additives. In addition to EP additives, these lubes contain rust inhibitors, defoamants, friction modifiers, thickeners, and Viscosity Index Improvers.
However, and since about 2000, most additive packages now contain "inactive" sulfur which is mediated by metal deactivators and which do not allow the sulfur to interact with the copper-alloy metals, but still allows the S-P additive to protect the gear teeth and bearings.

The problem with most OTS GL5 lubes in MT's is their viscoity and friction modifiers. While the OTS GL5 gear lubes are great for differentials, they do not possess the correct viscosity or friction modification for smooth cold weather shifting.

taken from here http://theoildrop.server101.com/ubb/ultima...c;f=56;t=000013

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If you are using expensive fully synthetic and off-roading I think you are wasting your hard earned dosh!

Much better to change all oils at 12,000 mile intervals or sooner if contaminated with water. Whether expensive fully synthetic or cheap(er) ATF if it's mixed with water it's the same cr*p!

doesn't rain here...... :P

Wot he said. :P

Never had water contamination, except on the floors after trying to wash the dust off. :lol: Also, we generally travel at higher speeds for much longer, in much higher ambient temperatures, hence synthetic oils are a much better idea. ;)

Paul :)

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