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      04-20-2013, 10:22 PM   #1
txz4
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Diff and Trans fluid change info

All of this is for the Z4M
First things first, here are the links you need to get a visual of the areas you're going to be working on.

http://www.bimmerfest.com/forums/sho...d.php?t=159395
(link courtesy of billswebspace.com)

Some helpful info:
1) i used 3 bottles of this:
http://www.ecstuning.com/BMW-Z4-M_Co...rain/ES197413/
2) i used two bottles of this:
http://www.ecstuning.com/BMW-Z4-M_Co...sion/ES263482/
3) you're going to need 2 diff plugs and 2 trans plugs as they are one time use:
http://www.ecstuning.com/BMW-Z4-M_Co...Plugs/ES42331/

http://www.ecstuning.com/BMW-Z4-M_Co...Plug/ES205597/
4) there have been problems for some people in accessing the upper trans plug, i planned ahead and used these:

http://www.harborfreight.com/12-piec...set-94961.html

all one piece and were the highest quality hex sockets ive seen. Here's the important part, they are also very stubby compared to all the other ones ive seen and owned.

5) you're going to need a pump of some sort to get the fluid in the trans and the diff. I used this:
http://www.harborfreight.com/multi-u...ump-66418.html

Works well, just be sure to pump slowly. Too fast and you're just going to tire yourself out and blow the hose out several times (ask me how i know).

Finally, the torque specs on the website are in NM, my torque wrench only has specs for lb/ft so here are some conversions for you:

Diff drain plug: 48 lb/ft
Diff fill plug: 45 lb/ft

Trans drain and fill plug: 26 lb/ft

be sure to lay something under your oil collector because it makes a huge mess if you aren't careful.

Last bit, all you need to do to get to the diff is remove the flimsy aluminum shield thing from around the resonator and the diff. Its like 7 8mm screws if i remember correctly.

Good luck and happy motoring!

Last edited by txz4; 04-23-2013 at 12:12 PM..
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      04-23-2013, 12:03 AM   #2
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This is great thanks!
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      04-23-2013, 04:33 AM   #3
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How many miles on your diff? I have about 102K miles and i'm sure the diff oil has not been touched or anything underneath for that matter. I have heard people replacing their diff and trans fluids, and once all fluids were replaced, it ruins the diff.

I've looked at other forums and some have mentioned when they replaced their oils, that the clean oils clean up the gunk stuck on the gears that let it work in the first place, rendering it useless. And ultimately having to replace the diff gears, etc.

Can anyone confirm this? I'd like to replace all my fluids and hope its not too late for a car like mine with high milage. Sounds to me like they just did not level the car properly and may have not put the right amount of oil in.

i'm not worried about having to level my car as i have a car lift, but i don't want to be a victim of replacing something when i could have just left it alone in the first place.
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      04-23-2013, 10:42 AM   #4
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///M cars have a much tighter tolerances and people tend to drive them more "spiritedly" Therefore requires trans and diff fluids changes every inspection 2 (approx. 50k miles depending on how you drive). Some change them on every inspections. My ///Mcoupe's trans and diff fluids looked clear when I last changed them out at 23k miles (inspection 1).

Non-M cars supposedly have "lifetime" fluids, but I would change them out every 50k miles or so, if it was my car. If you use the right fluids and complete you change procedure properly, there should NOT be any issues for swapping out the fluids. People reported issues either:
1. Used the wrong fluids
2. Improper refill procedures
3. There's probably something already wrong that prompted them to change out the fluids in the first place.

FWIW, I've changed out the "lifetime" fluids (transmission, both diffs, and transfer case) on my X5 at approximately 50k miles and everything is still running like a top now at 88k (knock on woods). All the fluids that came out were very dark, but didn't look/smell bad, but it's always great to have fresh fluids.

Bottom line, don't skimp/cheap out on fluids. Just pay up for the correct fluids and do it properly if you're going to go through the trouble of changing them.

Last edited by XMetal; 04-23-2013 at 10:53 AM..
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      04-23-2013, 12:18 PM   #5
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Quote:
Originally Posted by XMetal View Post
///M cars have a much tighter tolerances and people tend to drive them more "spiritedly" Therefore requires trans and diff fluids changes every inspection 2 (approx. 50k miles depending on how you drive). Some change them on every inspections. My ///Mcoupe's trans and diff fluids looked clear when I last changed them out at 23k miles (inspection 1).

Non-M cars supposedly have "lifetime" fluids, but I would change them out every 50k miles or so, if it was my car. If you use the right fluids and complete you change procedure properly, there should NOT be any issues for swapping out the fluids. People reported issues either:
1. Used the wrong fluids
2. Improper refill procedures
3. There's probably something already wrong that prompted them to change out the fluids in the first place.

FWIW, I've changed out the "lifetime" fluids (transmission, both diffs, and transfer case) on my X5 at approximately 50k miles and everything is still running like a top now at 88k (knock on woods). All the fluids that came out were very dark, but didn't look/smell bad, but it's always great to have fresh fluids.

Bottom line, don't skimp/cheap out on fluids. Just pay up for the correct fluids and do it properly if you're going to go through the trouble of changing them.
Totally agree with everything said above. Good upkeep is usually cheap insurance that everything will work correctly in the future. Im not sure about the older model years, but i know that on the 06-08 models the fluids are "lifetime" in regards to diff and trans. Whatever that means. I would assume that unless you are doing heavy duty track sessions regularly i would change the fluid every 50k miles on the z4.

I believe on mine im going to change every 30,000 as that is what i just hit. Furthermore, for M The schedule says to change diff and trans fluid every inspection II.
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      04-24-2013, 03:05 PM   #6
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People also use redline in the diff and MT, to save quite a bit of money, compared to using the OEM BMW stuff.
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      04-24-2013, 04:38 PM   #7
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Yeah i agree with xmetal too but i bought this car with 100K miles so for all i know the previous owner did god knows what. E85 diff and trans is "lifetime" use as well as your 2005's and up.

I ran this by with my local tech and he says if anything goes bad first, it would be the clutch, then the transmission. It's possible if it's been neglected, oil particles harden up into sludge and thats what helps to keep the trans in working order (for now). Once cleaned, it would no longer grip and it renders the transmission useless. Typically its the clutch that goes bad, but he says its possible the transmission itself would go bad if it's been abused i.e. peeling out from a stop or stressing it excessively which i know nothing of its driving past. I was told to be cautious about replacing the trans fluid.

To be sure i won't be stranded, i'll just put some money aside for a transmission replacement in case it does happen to go bad.
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