Differential Fluid Flush n' Fill

[AHay5]

Just flused and refilled mine with Redline 75w-140. The fluid flowing out had a dark red hue to it. I drove my car before so the fluid could flow out better and recommend it. Just another DIY peace in mind. Also curious to know if any potential seals will fail from flushing and filling with the new fluid.

[Dave540i6]

hello, thanks for the diy pics,
i just bought my 03 540i msport (135k) and it was missing the service records so i wanna start with the differential and later the transmission fluids what is the better fluid for the rear end 75w90 or 75w140? i stay in Texas and we do sometimes have 110f also does it matter if emsoil, redline,mobile 1 or rp?

thanks

[Jackcat559]

I use 75w90. Most guys go for Red Line or Mobile 1

[Dave540i6]

thanks for your response, i am leaning towards mobile1,but i do have one last question, i read that bmw recommends non-synthetic diff. fluid.... would u know if there is a difference?
thanks

[Jackcat559]

I've run synthetic for years with out any issues, but the decision is up to you

[Big Chaze]

Does both the tranny and the diff get filled to the top? If so, how many bottles of fluid for each?

[OnTheFence]

Mechanic told me my differential is leaking. Has anyone had this happen? Do you need to remove the axle to remove and reseal the diff? Before I pay to have that done, I might just top mine off, degrease it, and just keep an eye on how bad the leak looks.

[b2ke]

This presumably easy job became a nightmare earlier this morning as I struggled to remove the fill hole bolt. Unfortunately I decided to take the drain bolt out first so I can't take my car down the ramps. I'm surprised no one else has reported any difficulty. I will try again tomorrow and hopefully be able to take her on a drive and will report back with my results.

[jabela]

This presumably easy job became a nightmare earlier this morning as I struggled to remove the fill hole bolt. Unfortunately I decided to take the drain bolt out first so I can't take my car down the ramps. I'm surprised no one else has reported any difficulty. I will try again tomorrow and hopefully be able to take her on a drive and will report back with my results.

lol... seriously, every DIY says do the fill bolt first. I had a very hard time removing the diff fill bolts. I tried a 3 foot breaker bar but couldn't budge it. In the end, a few hits from a cheap electric impact gun loosened the bolts quite quickly. Make sure spray some penetrating fluid on it and leave it overnight.
Good luck!

[b2ke]

lol... seriously, every DIY says do the fill bolt first. I had a very hard time removing the diff fill bolts. I tried a 3 foot breaker bar but couldn't budge it. In the end, a few hits from a cheap electric impact gun loosened the bolts quite quickly. Make sure spray some penetrating fluid on it and leave it overnight.
Good luck!

I only read this thread. I guess I missed it.

[OnTheFence]

Instead of simply sticking a ratchet on the end of the hex bit (the normal way)
try putting the hex bit through a box end wrench before inserting into the fill plug.
This way, you can have more leverage with a cheater pipe on the end of the wrench.


Like this.

[JimLev]

Why not just put a pipe on the end of the ratchet or breaker bar?

[b2ke]

Update: Having changed the fluids at 167k miles and driving for the past few days I have concluded that the car is a little smoother. It is, however, not a night and day difference. Very subtle difference but I'm content because it was an easy job.

One other thing I noticed is that my mpg gauge in the cluster seems to be higher than usual by ~1-2 mpg. Although my cars computer (sorry I don't know the correct term) still says I'm at 16.1. On the other hand this could be a placebo

[frank9]

I bought a low profile floor jack, I made 4 jack pads off hockey pucks. I just ordered 2 more big read Jack stand, so I will have 4 jack stand.

My questions with the fluids, I got from BMW dealer:


1. Real diff fluid part # 07-51-2-293-972(synthetic), 1 bottle $22
2. Front diff fluid part # 83-22-295-532(hypoid axl), 2 bottles 2x$54=$108
3. Transfer Case fluid part #83-22-2-409-710(DTF 1:8325)1 bottle $53

on item 2, the bottle is 500ML, do I need 2 bottles? I see some diy job the real and front fluids is the same? I see someone use REDLINE fluiid, does anyone know the drain/Fill plugs and washer for real and front, and transfer case. I am confident I can change the real and front diff fluids, but with transfer case fluids, need take out the transfer case bracket, kind of hard. what kid basic hand pump do I need to use?

Any Advice

Thanks

Frank