Oil for the front and rear diff's

[Johno753]

So in the good book of landrover it says to put 90EP,80W90,85W90 I have been told to put GL4 in but I'm having a hard time finding that.
So what is the difference between GL4 and GL5 ?

[binch]

John will have the answer to this one for sure but the difference (as I understand it) is the GL4 was more friendly to bronze bush material, where GL5 is hard on them.      ???

I buy mine Greg distributors ;-)

[Red90]

There is no need for GL4 in the diffs.  It is just the gearbox that needs a GL4 and you want a lower viscosity there,  75W80 or 70W80.

Any old gear oil should be fine for the axles and transfer case.

[Red90]

So what is the difference between GL4 and GL5 ?

You probably did not want to ask this....

The "reality" is GL-5 is a standard that has more stringent wear tests.  https://www.lubrizol.com/DrivelineAdditives/AutomotiveGearOil/GL5.html  The problem is that when GL-5 came out, the manufacturers used certain sulfur compounds to provide high pressure wear resistance.  These compounds can corrode white metals (brass, bronze and so on).  A synchronized gearbox uses white metal on the synchros and problems were seen with corrosion.

Being able to pass the GL-5 test in no way means that the oil has corrosion problems, but everyone started to see things that way.  The API testing and rating system has nothing to do with white metal corrosion and really has no place in anything past the 70's....

Anyway, what lube manufacturers started to do is rate their gearbox oils as "GL-4" to indicate it was okay for white metals as the stupid public believed this was the case.  Most of these oils will pass all of the GL-5 tests, but you do what you do.  In addition, most modern GL-5 gear oils do not have corrosion issues.  Confused yet?

The whole topic is a complete and total mess and nobody wants to fix it.  Basically, if you are putting oil in a synchro box, make sure the manufacturer says it is okay for that use.  Oils for synchro boxes are quite different than gear oils.  You want high friction oils for the synchros, which is the opposite for something like a hypoid oil, where you want low friction.

[Johno753]

Thanks for that John, in my case I have the LT85 so it uses motor oil instead

[Red90]

Thanks for that John, in my case I have the LT85 so it uses motor oil instead

You could use one of the modern gearbox oils if you want....  The reason that they used to spec motor oil was that it has better friction and viscosity characteristics than what was available for gear oil.  These days, there are a lot of purpose built gearbox oils that are better.  They are expensive though and I've no idea if they really do much better than the gear oils.  Something like this http://www.redlineoil.com/product.aspx?pid=46&pcid=7 would be the right viscosity for an LT-85 or 95.

[ugly_90]

I use Shell Spirax HD 80W-90 EP, meets GL5.

It seems fairly important that you use an EP gear oil, I don't recall why.

I often buy my lubricants from UFA, as they usually carry high quality stock.

I use the conventional gear oil for the axles and spindles, and synthetic gear oil for the transfercase. synthetic MTL for the gearbox too.

[Johno753]

Only place I could get it in a larger quantity was John Deere so that's what I have at the mo lol

[RossM]

Ok so the can tire Motomaster 80w-90 GL5 that I just put in my gearbox and transfer case is bad, but it may be ok. Not to worry though they both leak worse than Ashley Madison web sight and will be empty soon enough!


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[Alex C]

Axle oils and transfer case

If its a used truck with unknown history, first thing to do is get it warm (drive  a 100 km ) then drain it this gets more oil and contamination out than cold.

flush you can do this with a mineral GL5 75w80 or 75W90, put it in and run for 1000 km then do a hot drain.

my preference flush with 15w40 engine oil, the detergents clean out the insides of the axle, can be done in 250 to 500 KM Do not load the axle no off roading now towing, hot drain.

final fill, or replacement oil for axles of known history and scheduled maintenance. find a good synthetic Mobil 1, Chevron, Shell, Petro Canada etc they all have them, you can pick up 20 Lt for $125 to $180, that will work for 2 full refils, diffs, X Fer, Front swivels, you can go with any of the 75W80, 75W90 type combinations, just make sure the second number is not greater than 90 i.e do not use 75W140, its two thick for our climate and in warm weather it runs very hot.

Last step, whatever you put in, fill a small plastic bottle with a cup full, then when its - 20 -40 etc, take a look at how the oil performs, if its separated, or frozen like an ice lolly, then you need to find a better oil or don't drive. with oil you get what you pay for.

Look at what a couple of tanks of fuel will cost you to run 80,000 km the way i see it paying $150 for 20lt of good oil that's going to run 80000km is a bargain.