Last updated:  2004.05.02

 ©  Text and Photo: Frode H. Haaland

 

Changing Gearbox Oil - the Clean Way

Using Difflocks "Oilsafe" Pump on Discovery Gearbox 

- and testing a new gearbox oil

 

Renewing oil in the gearboxes, and the axles for that matter, is a very dirty business. While the draining process is the worst on renewing engineoil, it's the filling that's the problem on especially the gearboxes. It's so cramped, and you can't just tilt an oilcan and pour into the boxes. Using a syringe-type of oilpump is usually considered the easiest and cleanest way for DIYs.

But now help is at hand, again from Difflock. Enter Oilsafe!

 

Old and new technology
Garages use a huge pump when renewing oils for the gearboxes, some even using pressurized air to move the stinking and high viscosity fluid. Some DIYs have been working a bit on old garden sprayers, but the EP 80/90 is so slow flowing at room temperature, it is often necessary to heat it a bit to enable it to flow through the lines, enabling the pump to work it.

The old oilsyringe is what most people use, it seems. The thick 80/90 oil makes a real mess of it all, but it does work, and it's cheap.
The web magazine and offroaders shop Difflock has enabled us to utilize a pump to fill the boxes, a sturdy unit made for pumping oil - removing the need for heating the slow flowing EP80/90...
The Oilsafe unit is a costly option, but the quality is so good you will be able to use it for the rest of your life. The plastic feels strong and good, there's a wire insert to make the oil flow easier, the tubing is thick, the spout at the end of the line is big and strong...in fact it feels like pros equipment

The kit consist of a drum (which come in several sizes), a "utility lid" (colour coded), and a pump.

You might want to purchase two drums (one for ATF and one for EP80/90). If so, you'll need another storage lid.

Prize is pretty high, though, as it usually is with good equipment:

5 litre drum: £10.20

Pump kit with utility lid: £44.22

If you want another drum, then add £10.20 for drum and £7,65 for a storage lid.

 

Draining main gearbox
The yellow circle marks the filler plug on the LT77 gearbox, while the red circle marks the drain plug.

There's also another drainplug - the gearbox extension housing drain plug.

Before doing anything else, open the filler plug. If you overdone the tightening last time, you might encounter problems opening this plug - so if you have already drained the box, you're thorughly standed!
Place a funnel and a container under the drain plug, and carefully open and remove the plug. It will initially flow very fast!
The plug is magnetic, so particles from the gearbox stick to it. As can be seen here, there's no grains or serious grinding of gears going on in this box - it's just the usual filing down of the cogs.

Wipe the plug thoroughly clean.

Seen on the picture is also the copper sealing washer, which has to be renewed.

You have now been touching oil for two or three minutes - and the latex-gloves are already dissolving. They are all but useless. This is the time you put the blue nitrile gloves from Difflock on your shoppinglist: they do survive these fluids!
When it stops flowing, it's time to drain from the gearbox extension housing. Move funnel rearwards, and undo the big nut. There's an oilfilter in there, and it takes a bit of fiddling to get it out.

While the rest of the oil is draining, take the oilfilter to your workbench, and clean it in white spirit or smth.

Clean the plug thoroughly, and fit new copperwashers. If you do not change these, they will leak. If you got the wrong ones, or forgot all about it, you can heat the old washer until it glows, let it cool down, and refit. It use to work.

 

Refilling - with Ovoline
The LT77 utilize ATF (Automatic Transmission Fluid), a red oil otherwise used for automatics. It is supposed to be renewed at 20,000km/once a year (the oil here used is claimed to last 2-3 times that).

Difflock supplies Ovoline MT75D as an alternative oil, claimed to give much improved shifting. It's a fully synthetic gearoil with all kinds of advanced additives which you and me have no knowledge nor interest of: We just want an oil that does it's best and gives us the best chance of shifting gears up and down every day and hopefully the gearbox will never be in need of a restore...

Otto has had timely renewals, I myself have run through four renewals of gearbox oil. Last time with Shell Donax TF.

The shifting use to be a bit better when oil is new. The box is still pretty tight, and only problem is synchronisation going down to 2.gear, especially when cold.

When renewing with Ovoline, the old oil had only 10,000km running, so it should be in pretty good shape - thus making it more difficult for the Ovoline oil to show its best. Ideal testing condition!
The Oilsafe drum has both gallon and litre markings.

 The LT77 takes 2,65 litres, so three cans of oil were poured into it.

A nice detail of the Oilsafe drum, is the big and wellrounded handle, making carrying easy.

Then it's only a matter of creeping under the vehicle again, and put the spout into the filler hole.

The spout is thick, and even has a groove on it, to keep it from slipping. A very well made detail!
Then it is only a matter of pumping. Which you do not do from under the vehicle. After hooking in the line into the box, you get out from under the vehicle, stand up, and start pumping - peeping under the vehicle from time to time to check everything is still OK.
It is not a pressurized pump, so if you stop pumping, the flow stops. I counted something like 30 or 40 strokes to move the 3 litres of ATF-fluid.

It has never been this easy, nor any cleaner!

The Oilsafe pump is expensive, but saves you a lot of mess, and I will highly recommend it to anyone servicing a Land Rover on their own.

I would suggest purchasing two drums of 5 litres each, and use it for ATF (gearbox) and EP80/90 oil (transferbox, axles and swivel housing).

You do not need this kind of equipment for engine oil, but if you do want it - there's some nice spout-options for that kind of use. Makes your garage tidyer with a lineup of colourcoded drums of differing sizes, but 2 is what you really need!
Last question is how to remove the oboslete oil still left in the tube, pumping doesn't work when the drum is empty... Answer is to drain it by removing the pump from the drum, and hang the filler up high with something to take the oil beneath the pump. Leave it hanging for some time, it drips slowly out of the pump due to gravity.

 

How was the Ovoline MTF 75D?
There has been quite a hype around this oil, improving shifting beyond what you could possibly believe and so on. As with anything that is "just the best", "improves fuel economy", "like silk", no hesitation, it's probably a bit exaggerated.

My wife couldn't detect any change, which would have been a real test for confirming the hype. Leaving the hype, what do we find?

Wife not detecting any change, doesn't mean the gearbox feels like before! For me, it is the best oil I have ever had in my gearbox.

All the way from minus 10 centigrade to +25º, over several thousand kilometers, it has given a very smooth shifting, the lever moves easily and you can literally feel things moving more easily and nicely inside the box. Shifting on cold days is probably a good test for the oil - and it does outperform other oils I have used. From the feeling of this oil, things run a bit smoother inside the box, thus should also give less wear.

But not like silk, not all quiet,  no no-problem on 2.gear synchronisation and so on.

Don't expect anything to work like magic - an old box is still an old box. It is not a revelation in my gearbox at least. There's still a bit of synchronisation problems going down to second gear, there's still some sound from the box, and so on. What an oil can do, is make the best of what is already there, inside the box. Make the cogs and synchrorings slide and work to their best, cushioning all the metal-to-metal workings that are going on inside the box. A good base oil and good additives is what assures this.

What the Ovoline is, is a very high quality oil which beyond my doubt is the best I've ever tried, and which I would highly recommend as it will probably lease a better life for both you and your gearbox. 

But there's no magic to it, just someone knowledgeable having worked out which kind of oil and additives would suit our gearboxes the best. They have proven their competence, not their magic wand!