Rear Diff fluid change DIY

[N55Msport]

Hello, My 2016 M3 needed a rear diff fluid change as noted on page 45 of the maintenance manual. It should be replaced after the 1200 mile breakin period and after the 5th oil change. I tried to explain to a BMW service advisor that I am past 5 oil changes, still under warranty at 41,000 miles, and about to take a long summer road trip and would like to have it changed. There is a note on the same page that mentions this particular job won't appear via the CBS but he said they would not change the fluid until the system said to change it. Even after showing him the note he was still confused (Head bang) hence the super easy DIY.
I was qouted $60.00 a liter for the rear diff fluid, 2 hours of labor at $168.00 per hour and $18.00 for each drain and fill plug.

Total cost using my BMWCCA card at the same dealership...$16.99 for both plugs
$54.00 for 2 litres of 75 W140
$12.00 fluid transfer pump at Autozone.
Total time :45 minutes which included doing my manual gearbox fluid.

Pictures say it all, so I'll paraphrase the job here:
1) Safely jack up car and confirm it is level. I always go overboard on safety using back up jacks only because I was doing the manual gearbox fluid at the same time. My Rhino Ramps provide plenty of room.

2) Using 14 mm hex drive, undo fill plug first.

3) Undo drain plug and allow fluid to empty into pan. After 39,000 miles it was only slighty darker than the fresh fluid going in.

4) Secure drain bolt and torque to 45 nm.

5) Using a fluid transfer pump, pump about 1.5 litres of fluid into diff until it flows out the hole. Mine literally took a bottle and a half.

6) Secure fill bolt and torque to 60 nm.

7) Clean any excess fluid off rear diff with Brake Kleen or similar parts cleaner.

8) Enjoy

Notes: Bring the rear diff up to temperature by driving around. I did a mix of back roads/highway etc. Just dont change it cold.

Even after :30 minutes of cooling with a fan blowing under the car, the fluid is still failry hot so be careful.

[gatorfast]

Thanks for the write up. Very easy job.

[MrSmartyPants]

BMW made both of those jobs stupid easy. I did the same at 40k this spring.

Also added an ECS magnetic drain plug on the diff. Couldn't find one for the trans.

[N55Msport]

Originally Posted by MrSmartyPants

BMW made both of those jobs stupid easy. I did the same at 40k this spring.

Also added an ECS magnetic drain plug on the diff. Couldn't find one for the trans.

Great idea on the diff magnet. I also could not find one for the transmission.

[longlasting]

Ty for diy saved to reference

[hC1001]

Thanks for the DIY.

Just one question, Are you sure its 1.5L? The tranny is 1.5L but everywhere else i see the diff is 1L capacity including the TIS. Can someone clarify this for me so i wont be stuck ordering another bottle of diff fluid?
Thanks.

[ellipsis212]

It's the same as pretty much every BMW ever

[hC1001]

I just drained my diff and measured 1 liter for anyone whos looking for the correct f80/82 differential fluid capacity.

[knightarmor]

Thank you for this DIY.

[carM3kee]

Are there other recommended diff fluid? Or is OEM BMW diff fluid the only bottle everyone uses?

[BlownOne]

Originally Posted by carM3kee

Are there other recommended diff fluid? Or is OEM BMW diff fluid the only bottle everyone uses?

Use oem fluid as the diff can get noisy if the fluid doesn’t have the correct friction modifiers.

[BlownOne]

I completely drained my diff and it only took slightly more than 1L before seeping out of the fill hole, even with the car tilted slightly towards the front. Old fluid was super dark compared to the golden colored new, but I’m not sure when it was last changed, assuming 1,200 miles and it’s at 44k now. Fill and drain plugs have rubber o-rings and are reusable so I didn’t replace mine. Plan on doing it again in 10k miles since the fluid was so dark (as a flush basically) and I already have new fluid.

Current list cost is $45.xx per liter for fluid

[gatorfast]

^ fluid color is not a good nor reliable indication of whether it is still adequately performing or not. Sending it off to be analyzed for particles, viscosity, additives, etc would tell you whether it was still good fluid or not.

[andrei.m4]

First unscrew fill plug, if you can t unsrew after drain for any reason, broken or i don t know you will remain without oil in diff.

[BlownOne]

Originally Posted by gatorfast

^ fluid color is not a good nor reliable indication of whether it is still adequately performing or not. Sending it off to be analyzed for particles, viscosity, additives, etc would tell you whether it was still good fluid or not.

Yes I’m aware that’s the scientific way to do it, however new fluid is always better than old fluid, even if you’re not analyzing.

Originally Posted by andrei.m4

First unscrew fill plug, if you can t unsrew after drain for any reason, broken or i don t know you will remain without oil in diff.

+1. Always remove fill plug first to ensure you can refill

[x.shell]

Originally Posted by MrSmartyPants

BMW made both of those jobs stupid easy. I did the same at 40k this spring.

Also added an ECS magnetic drain plug on the diff. Couldn't find one for the trans.

Originally Posted by N55Msport

Great idea on the diff magnet. I also could not find one for the transmission.

I used an ECS magnetic drain plug on my last oil change. Then I read all these bad reviews online about how they sheered off when trying to remove it. Not trying to be an alarmist, and maybe most of them was user error... but I'm gonna be really careful removing it on my next oil change and stick to the OEM plugs even if I have to reuse them.

Fantastic DIY btw. Clear and concise.

[andrei.m4]

Originally Posted by BlownOne

+1. Always remove drain plug first to ensure you can refill

Again, you mean fill plug first

[BlownOne]

Originally Posted by andrei.m4

Again, you mean fill plug first

Good catch lmao

[BlownOne]

....

[GoodtoGo]

Originally Posted by carM3kee

Are there other recommended diff fluid? Or is OEM BMW diff fluid the only bottle everyone uses?

Motul Gear Competition 75W140

[TopJimmy]

Originally Posted by carM3kee

Are there other recommended diff fluid? Or is OEM BMW diff fluid the only bottle everyone uses?

Today on the F80 I drained the Diff and refilled with Red Line 75W110 full synthetic GL-5 gear oil. The case took slightly more than 1 quart (it's 1 liter as per BMW). I hear no extra noise when using this diff oil.

I also did the 6MT gearbox with 1.5 quarts of Red Line DCTF. The shifter glides well and gear selection has a nice feel (not overly slippery). No extra sound here either. All good.

[Crazy Penguin]

Which are the trans fill and drain plugs! Did I miss that?