[Delighted_Jester]

I changed my diff fluid last week in my 2020 M340i w/M Sport Differential. I used Hypoid Axle Oil G-4 P/N83222447362. Pictured is the old fluid versus the new G-4 axle oil. I also used the differential tool from FCP Euro B33000000.

[dhock_holiday]

Pretty dark for 30K, I guess I’ll be doing mine earlier.

[Delighted_Jester]

Originally Posted by dhock_holiday

Pretty dark for 30K, I guess I’ll be doing mine earlier.

I think BMW recommends changing it at 60k. Ill do it every 50 with the transmission from now on i think.

[weinerbarn]

I wonder if a lot of that has to be the friction material from initial break-in. This was from my X5MC at the 1200 mile service. Did you see a lot of suspended metal in the fluid?

[Delighted_Jester]

Originally Posted by weinerbarn

I wonder if a lot of that has to be the friction material from initial break-in.

Now that you posted that pic, i feel a little better. I dont really see anything suspended in my fluid. Your fluid looked worse than mine did but being that its only 1200 miles im certain BMW factory filled fluid IS NOT the specified G-4 fluid, rather something else that is "forever fluid".

How did yoy extract the fluid? I used that tool and a $40 oil pump from northern tool. Im sure your diff also lacks a drain plug?

[weinerbarn]

Originally Posted by Delighted_Jester

Now that you posted that pic, i feel a little better. I dont really see anything suspended in my fluid. Your fluid looked worse than mine did but being that its only 1200 miles im certain BMW factory filled fluid IS NOT the specified G-4 fluid, rather something else that is "forever fluid".

How did yoy extract the fluid? I used that tool and a $40 oil pump from northern tool. Im sure your diff also lacks a drain plug?

Fortunately the rear diff on mine (F95) has separate drain and fill plugs. I used a "syringe" from Harbor Freight to refill. I think it's called a "Lubricant Suction Gun". I'm probably going to buy one of the ratchet pumps for doing the transfer case and transmission fill. I haven't the oppty to change the fluid yet in either the 540i or M340i yet.

[hayko_M340]

Well that's not good to see, just passed 46K and diff is untouched and "sweating" per dealer. Took it in and they said it's normal per TSB. Gonna try taking it in again before warranty ends to hopefully get a new cover and some fresh fluid in there.

[Delighted_Jester]

Originally Posted by hayko_M340

Well that's not good to see, just passed 46K and diff is untouched and "sweating" per dealer. Took it in and they said it's normal per TSB. Gonna try taking it in again before warranty ends to hopefully get a new cover and some fresh fluid in there.

Sorry to hear about that. If you get a new cover, youll also get new fluid, so i hope they replace it for you! Leaks are never "normal" but some can be ignored. Thankfully my 2020 does not sweat any fluid.

[hayko_M340]

Thought I'd update, got it changed out at 50K and I'm glad I did. Fluid came out looking like metallic nail polish. Measured 700ML that came out and ended up filling 900ML. Clunk/thump severely reduced especially when cold, obvious since it seeped out a good amount. Highly recommend if you plan on keeping long term and if driven hard.