Thread: tips for gear box and diff oil change?

Originally Posted by luke68

Just unplugged the breathers of both the g/box & transfer. Transfer had about 100ml of brown oil in it. Put new 85-140 gear oil in it . A lot quieter and no more grinding noise when in low range. I reverted back to ATF111(dextron3) for the gearbox as I found that the mtf94 was not as easy or smooth shifting as the old stuff. I know the updated bulletin says use the newer synthetic oil but I find the auto oil is much better.Ps. 300TDI with 340k
Cheers luke

This is an old thread so I'm not sure if this will get answered by Luke68 or not...but do you mean by this that your breathers had 100ml of brown oil in the hoses or the whole transfer case only had 100ml in it??? That sounds like a very low transfer case!!

I'm just looking in to how to check and change the diff and transfer case fluids hence the search of an old thread...oh also, when people talk about the axle fluids is this something different or is this one and the same as the diff oil? I'm a bit confused!

Biggest thing to remember with changing dif/gearbox oils is to undo the fill plug BEFORE you drain the oil out! Depending upon previous owners/mechanics, the diff fill plugs may be plastic, and can very easily be rounded/stripped. Repco or the like will usually have steel replacement ones, but its handy to check first.
You'll need some sort of pump to fill the front diff, nowhere near as much room there as the rear.
The diffs will take a bit over 1.5 litres each, and the transfer case around the same or a bit more. Not sure off the top of my head about the manual gearbox. (I'm an old fart, so all mine are auto's! )

Originally Posted by donh54

Biggest thing to remember with changing dif/gearbox oils is to undo the fill plug BEFORE you drain the oil out! Depending upon previous owners/mechanics, the diff fill plugs may be plastic, and can very easily be rounded/stripped. Repco or the like will usually have steel replacement ones, but its handy to check first.
You'll need some sort of pump to fill the front diff, nowhere near as much room there as the rear.
The diffs will take a bit over 1.5 litres each, and the transfer case around the same or a bit more. Not sure off the top of my head about the manual gearbox. (I'm an old fart, so all mine are auto's! )

Cheers for that, I've read a few things that say that too...don't want to be stuck with nothing in your diffs if you can't fill them up again!

The manual gearbox sounds like it's just the transfer case oil but I'm still wondering if, when people talk about axle oil, if that's something different again or if this is just referring to the diff oil.

Maybe let's just start from scratch...how many different fluids are there to change on a manual 300tdi Disco 1? Not counting engine oil, I count the two diffs and the transfer case. Are there any more I'm not aware of?

Caveat...I haven't read the owners manual yet I've just been looking online so far.

Axle/diff is interchangeable, just try not to use diff fluid in a manual gearbox unless it's a transaxle fluid.

ATF's (or engine oil) were often specified in manual gearboxes back in the day as manual transmission fluids weren't available.

Manual trans fluids have more appropriate frictional characteristics for synchro engagement compared to ATF's or engine oil.
And, IMO, ATF's are often a little light in viscosity for best gear/bearing life.

Originally Posted by rick130

Axle/diff is interchangeable, just try not to use diff fluid in a manual gearbox unless it's a transaxle fluid.

ATF's (or engine oil) were often specified in manual gearboxes back in the day as manual transmission fluids weren't available.

Manual trans fluids have more appropriate frictional characteristics for synchro engagement compared to ATF's or engine oil.
And, IMO, ATF's are often a little light in viscosity for best gear/bearing life.

I think I'm getting a bit confused...is there a such thing as changing the axle oil? Is that something that's different from changing the diff oil or is changing the axle oil and the diff oil referring to the exact same oil, that sits in the diff itself?

Axle oil, diff oil - same thing. The diff housing is oil filled and contains the diff gears and axles.

In the front of a D1 there is also the swivel pin housing (contains CV joint), which is normally grease filled, but can also be oil filled.