Changing the Differential Fluid

[IMPRMNS]

I've never done changed diff fluid before so I am going to put my pride in the backseat and just ask. Are these these the drain/fill ports?

From a process standpoint, my understanding is that this is pretty simple.

1) Start with a warm axle
2) Remove fill plug
3) Remove drain plug & drain
4) Replace drain plug; torque to 31Nm
5) Fill with SAE 80w90; 2.1L for both front and back
6) Replace fill plug; toque to 31Nm

Am I missing anything?

 

[Clark Kent]

I've never done changed diff fluid before so I am going to put my pride in the backseat and just ask. Are these these the drain/fill ports?

From a process standpoint, my understanding is that this is pretty simple.

1) Start with a warm axle
2) Remove fill plug
3) Remove drain plug & drain
4) Replace drain plug; torque to 31Nm
5) Fill with SAE 80w90; 2.1L for both front and back
6) Replace fill plug; toque to 31Nm

Am I missing anything?

Yes they are the drain and fill ports.

7) Check all plugs for leaks after the first drive.

 

[ECrider]

I've never done changed diff fluid before so I am going to put my pride in the backseat and just ask. Are these these the drain/fill ports?

From a process standpoint, my understanding is that this is pretty simple.

1) Start with a warm axle
2) Remove fill plug
3) Remove drain plug & drain
4) Replace drain plug; torque to 31Nm
5) Fill with SAE 80w90; 2.1L for both front and back
6) Replace fill plug; toque to 31Nm

Am I missing anything?

Your front diff fillet has much better access than mine - right hand drive here

Thinking that next time I need fill mine then will jack the body up as best I can which gives a much better angle of attack with a ratchet

 

[IMPRMNS]

Another newbie question…can one overfill an axle? My differentials took more than the cited 2.1L of 80w-90 when filling to the level of the fill hole.

 

[255/85]

You'll know if it starts burping out of the breather tube.

In all seriousness, overfilling can lead to air entrainment in the fluid - otherwise known as frothing. Reduced lubrication is the result. You should be fine at the top of the fill hole.

 

[ECrider]

If you still have the one way valve OEM breather and it is clear of crap and working properly then should expel any over fill.

I reckon the diff takes a good 2.5l upto the filler.

I don't think this is a bad amount.

I do however think the OWM breather is flawed and best replaced with a neutral pipe arrangement.

 

[JKAlpine]

What size the the plug? Is it hex or torq?

 

[CountyV8]

It is NOT fill to spill check it needs to be filled bellow the spill level.

Post in thread 'Diff oil level measuring tool?'

Mar 3, 2025

Why do you want to buy such a tool? Make one.! All you need is a wire hook with a leg length of approx. 35 mm on the short side. If you then fill the differential with exactly 2.1 liters of oil, the oil level will be approx. 23 mm below the filler opening. You can always check the oil level using a corresponding mark on the hook mentioned above. However, unless you do have an oil loss in the differential area, there will hardly be any reason to check the oil level. Given the price of the differential oil (approx. 5 euros per liter), it should be much easier to simply change the oil every...

• Greasemonkey

• 

 

[abbeyroad]

Has anyone sourced a front and rear diff fluid change kit with INEOS factory parts? Typically, they require a least a crush washer of some type. I know my Raptor actually treats the plug itself as one time use.

 

[C-Mack]

I use finely graduated plastic containers (like a 1 gal. clear painters bucket with metric and standard measurement marks) to routinely drain the oil from the diffs/transfer boxes on all my vehicles to see what actually drains out and compare it to the specified amount in the manual to see if any has leaked. More often than not the amount drained closely matches what is in the manual and I make sure to put the specified amount back in with a hand operated fluid pump.

Never had an issue using this method but one very important key is to make sure the vehicle is perfectly level front to back and side to side before starting. It seems a lot of modern vehicles don’t use the fill hole level method and instead specify the exact amount to put in. Also lifted vehicles where the axle diffs have rotated slightly will give you different readings or in some cases lower the fill hole low enough you can’t get the correct amount back in without jacking the axle up a bit so it pays to be precise.

 

[etbandit]

This is what the service manual recommends. It says to fill with a max volume of 2.1L of diff oil.

 

[CountyV8]

I still wonder why not fill to spill??
Euro nonsense (insert own conspiracy theory here)

 

[255/85]

You'll know if it starts burping out of the breather tube.

In all seriousness, overfilling can lead to air entrainment in the fluid - otherwise known as frothing. Reduced lubrication is the result. You should be fine at the top of the fill hole.

I'm changing my opinion here since I can't edit my original post...

Stick with the factory fluid replacement of 2.1 litres.

 

[255/85]

I still wonder why not fill to spill??
Euro nonsense (insert own conspiracy theory here)

Perhaps some sort of internal flow pattern may be at work inside the housings?

 

[CountyV8]

Perhaps some sort of internal flow pattern may be at work inside the housings?

If thats the case what is the difference between 2.1 L and fill to spill??

 

[abbeyroad]

It says to fill with a max volume of 2.1L of diff oil.


View attachment 7906174

View attachment 7906172

But what about the rear diff?

 

[Zimm]

Perhaps some sort of internal flow pattern may be at work inside the housings?

i think you're overthinking it. Telling people to fill until it runs out, isn't environmental conscious.

 

[Zimm]

1) the fill port is about in the same location as all other fill to spill units. This isn't some new fangled clutch pack differential, it's roman era technology, nothing has changed, people are fretting too much. Unless you've got a contaminant in there, you're not going to be creating a bubble bath.

2) A tad more oil may cause a tad more heat, as the oil itself is a heatsink for the gears. 2.4l as opposed to 2.1l means the volume of oil has increased, but the surface area it needs to make contact with to cool has not, so the temp will rise a bit, but it's not in the same realm as the temp rising a bit because of too little oil, and metal bits heating up. It's more like that caused by a slightly warmer day outside. I don't believe it's oil friction. The energy entering the system is the same, it just isn't leaving as heat as readily.

If you've moved the factory stop setting on the axles for a greater radius, but you're worried about .3l of oil over the recommended fill, your risk priorities may need adjusting.

 

[NQ94]

See where the oil level is in relation to the axle shafts are in the housing. They're likely keeping the oil level below the drive axle in the axle housing as the axle doesn't need to be in an oil bath. Looking at the diagram the fill plug is above the axles

 

[Zimm]

See where the oil level is in relation to the axle shafts are in the housing. They're likely keeping the oil level below the drive axle in the axle housing as the axle doesn't need to be in an oil bath. Looking at the diagram the fill plug is above the axles

I'm not saying you're wrong, but it with it slinging around in there at 6-700 rpm, the axle shafts are going to get bathed anyway. It's not an issue to consider either way. look at where his fill line is, then look at a dana 60 diff cover, or a sterling 10.5 diff cover, or whatever diff cover you want, that are all fill to spill, and you'll see they ae where the ineos fill bung is. This is a complete nothingburger.

View: https://www.youtube.com/watch?v=9-yG3D3JBRs


and he has a few more if you want to search.


youll also notice the oil at this speed gets airated. it can't be avoided. You dont need a special tool or a turkey baster to fill to a precise level in a diff. if you're that concerned, use the first digit of your finger. Jesus.