E86 Diff Oil Change

[Beesza]

I changed the diff oil in my coupe last night. I hadn’t previously found much on the forum regarding doing this on a facelift car so thought I would share a few notes and pictures. The job was much easier than I had expected.

My car has done 136k so I thought the life-of-type oil was probably close to its death bed. I wasn’t having any problems, just thought it would be sensible maintenance.

Upon jacking the car up and ensuring it was level. I found the diff filling port between the rear cross braces. Using a 14mm Allen key on a universal joint, I was able to remove the plug without the need to disassemble anything.

I could not find a drain plug so I used tubes and a hand pump to suck out the old oil through the filling port. It was a cloudly dark brown colour so definitely in need of changing. I got approximately 800ml out (managed to knock the bottle over before taking the photo )

I refilled it with Millers 75w90 transmission oil. About 1.2 litres when in before it started to overflow. For comparison, the new oil was a pale clear yellow colour.

Pro tip: the higher you can raise the car, the easier this job will be.

Pump was £7 from eBay and worked really well. Oil was about £12.50 a litre.

 

[Zedebee]

Nice one
Any different for a pre-LCI E85 do you think?

 

[Beesza]

Nice one
Any different for a pre-LCI E85 do you think?

From the YouTube videos I have seen, pre-facelift z4’s have a drain plug on the side of the diff. You need to remove the rear under tray to get to this. Search YouTube for z4 diff oil change and you’ll find a Slovakian guy doing a good walk through of the job on his 2.5i

 

[Zedebee]

Excellent, thank you.

 

[markplant]

Nice one
Any different for a pre-LCI E85 do you think?

Just as note an you might already be aware, before undoing the drain plug loosen the fill plug, because you don't want to drain out the oil an then find out you can't undo the filler

 

[Brouse]

Ah brilliant you legend, now I know where that elusive filling point is!!! I thought it was higher up.

 

[Gregory_tolson]

That stuff smells amazing doesnt it lol

 

[colb]

The fill for life BMW would have you believe is nonsense, its a sales gimmick that will cover the cars warranty period from new. In engineering terms the oil within the diff has to contend with the bevel gears inside and these have a chopping effect on the oil molecules and its additives that make it a gear oil to contend with the chopping and pressure the oil has to sustain in operation. Given these conditions nothing is going to last forever and thats the same for manual gearbox fluids. Still some debate on changing Automatic gearbox fluid, some say leave it alone, others say change it and the internal filter.

 

[Gregory_tolson]

Yeah, i have a '14 Ford Fusion and it has no dipstick for the automatic transmission. Calling the dealership they said its lifetime fluid. I just drained and filled it twice to get most of it out at 70k miles. Did another drain and fill at 100k miles and the fluid was the proper red wine color. Id change the filter if i could but it has no pan, only a drain plug. Hoping the fluid change over time will be enough to prolong its life. It shifts perfectly.

 

[Beesza]

That stuff smells amazing doesnt it lol

Spilt some in the garage. Whole place smells awesome now.