[dula]

Hey guys, I plan on changing all the fluids that my car has been long overdue for IMO. I finally have to time to do this myself because of quarantine so might as well.

Car F30 335xi with the pwg n55

Engine Oil (I change this every 8k)
Transmission Fluid (I'm at 115k and it has never been changed)
Brake Fluid (Never been changed)
Diff Fluid (Never been changed)
Transfer Case Fluid (Never been changed)

*Canadian so I use KM not Miles*

My initial plan was to do all this at 100k but life happens ya know.

I've been trying to find some solid sources on how many litres of fluid I'll need for the transmission but I've had fellow owners tell me they used 6-7 Litres while the dealership is telling me I'd need 8.5 so let me know if you know otherwise please.

[thejeremyman9]

Transmission fluid is very involved, just FYI. It's the most complex DIY of everything you listed, by far. You need to very carefully follow procedures, correct temps, etc. Just want to make sure you are aware it is much more than a drain and fill type of thing. I believe you need access to ISTA to do it, but not 100% sure if you can work around that.

EDIT: This assumes 8AT

[IraHayes]

What Jeremy said regarding the trans, if it is an 8HP. ZF has a very specific procedure. If memory serves, it holds 8 qts. You'll get about half of that out with a standard trans service. The transmission service kits they sell usually come with 7 quarts. You need to be able to monitor the trans temp to properly fill the trans. You'll need an app or a scan tool to monitor the temp, though some guys just use one of those laser temperature guns. Some say you need to reset transmission adaptations when done, in which case you'll need a scan tool like the Schwaben scan tool made by Foxwell. ECS tuning sells these. That said, nowhere in the instructions from ZF does it say that adaptations need to be reset, so I wouldn't worry about that part.

https://documentcloud.adobe.com/link...e-dd19bebac3f2

[BMWILUVU]

The transmission oil change is the most involved and potentially dangerous DIY. ISTA only guided the steps and monitored the transmission temperature. You don't really need it if you have an IR temperature tool.

[ooshnoo]

Here's instructions on changing the transmission fluid


https://blog.fcpeuro.com/how-to-chan...smission-fluid

I followed it and it was easy...it took a while, but it was easy.

[andino]

I did the transmission fluid recently using ISTA and its not too bad. FCP's instructions are a great primer for doing it. Its actually pretty easy to do imo; just a bit messy if you splill fluid. I'd recommend a good fluid pump over the cheapy one that fcp recommends in their kit however!

The front diff is pretty easy to do on my car. I just needed an 8" extension to reach the fill plug through the wheel on the driver side. Draining is dead simple on the front as there's a drain plug.

t-case is a bit tight but fairly straightforward from what I could see. You'll want to support the trans and drop the transmission brace to get access to the fill plug. You'll also need a flexible extractor hose or a hook style one to get to the bottom of the case while under the car to suck out the fluid.

Rear diff on my car was a bit of a pain to get to the fill plug. There's a vibration damper in the way along with some v bracing specific to the f31. I suspect it'll be easier on other models but once you figure out how to get around the obstructions, the rear diff is also dead simple. Not sure why BMW decided to remove the drain plugs on the t-case and diff but it really makes things annoying!

[kingmonkey8]

The diff fluid change is not an easy job. On my car there was no drainage bolt. There is a hole for filling but not for draining. Unless you take the diff out and remove the back panel.
I wouldn't really recommend doing it unless necessary.

[pw0n]

Originally Posted by andino

I did the transmission fluid recently using ISTA and its not too bad. FCP's instructions are a great primer for doing it. Its actually pretty easy to do imo; just a bit messy if you splill fluid. I'd recommend a good fluid pump over the cheapy one that fcp recommends in their kit however!

The front diff is pretty easy to do on my car. I just needed an 8" extension to reach the fill plug through the wheel on the driver side. Draining is dead simple on the front as there's a drain plug.

t-case is a bit tight but fairly straightforward from what I could see. You'll want to support the trans and drop the transmission brace to get access to the fill plug. You'll also need a flexible extractor hose or a hook style one to get to the bottom of the case while under the car to suck out the fluid.

Rear diff on my car was a bit of a pain to get to the fill plug. There's a vibration damper in the way along with some v bracing specific to the f31. I suspect it'll be easier on other models but once you figure out how to get around the obstructions, the rear diff is also dead simple. Not sure why BMW decided to remove the drain plugs on the t-case and diff but it really makes things annoying!

Thanks for sharing. I plan on doing this myself in the coming weeks via ISTA. Out of curiosity, does the car maintain the transmission temperature levels once it reaches the minimum threshold? e.g., if it requires to be 40-50 C, once it hits 40 C, does it stay below 50 C?

Also, I got the same cheap pump... lol. Any tips/tricks for the exact pump?

[pw0n]

Originally Posted by kingmonkey8

The diff fluid change is not an easy job. On my car there was no drainage bolt. There is a hole for filling but not for draining. Unless you take the diff out and remove the back panel.
I wouldn't really recommend doing it unless necessary.

I haven't tried this yet, but I've seen videos where the fluid is extracted/pumped out using a fluid pump - seems fairly doable. I also bought this 45 degree hook/adapter specifically for extracting diff fluid.
https://www.ebay.com/itm/Differentia...53.m2749.l2649

(in case eBay links expire, which I see all too often, refer to image below)

[andino]

Originally Posted by pw0n

Thanks for sharing. I plan on doing this myself in the coming weeks via ISTA. Out of curiosity, does the car maintain the transmission temperature levels once it reaches the minimum threshold? e.g., if it requires to be 40-50 C, once it hits 40 C, does it stay below 50 C?

Also, I got the same cheap pump... lol. Any tips/tricks for the exact pump?

Temps still go up very slowly once you hit the min temp. I was able to get all the fluid in before it got any hotter than the min temp.

Tips for the pump are to make sure your car is high enough in the air to comfortably swap bottles if you want to stay under the car. I'd recommend a friend help you swap the bottles out though as I did it by myself and got covered in that smelly fluid!

Also try and angle the tip that goes into the pan slightly downward and towards the back of the pan otherwise you'll get fluid reflecting off the top of the trans and ends up on the floor (or in my case, on my shirt lmao).

[ktw]

Originally Posted by kingmonkey8

The diff fluid change is not an easy job. On my car there was no drainage bolt. There is a hole for filling but not for draining. Unless you take the diff out and remove the back panel.
I wouldn't really recommend doing it unless necessary.

I was able to remove and add ~800 ml fairly easily from my rear diff fill port using a syringe type extraction/filling pump, some silicone tube, and a wire coat hanger cut and placed inside the tube to enable bending/directing the silicone tube. I'm sure with a bit more time/creativity you could get more of the 1.5 L quoted volume out. Getting to the fill port plug out was a bit more of a pain than expected because of some braces and vibration dampers in the way, but nothing too difficult to remove.

The rear diff fluid was noticeably more discolored and burnt smelling than the front diff fluid on my xDrive at ~50k miles, so I'm planning to change it more frequently. (Also because it's not a complete drain.)

[kdad]

Newbie question on fluid pumps. Can the same pump be used for changing different fluids, assuming it's wiped down / sprayed with brake cleaner in between? Or do you guys use different pumps for different jobs? Thx

[Jvac]

Originally Posted by ktw

I was able to remove and add ~800 ml fairly easily from my rear diff fill port using a syringe type extraction/filling pump, some silicone tube, and a wire coat hanger cut and placed inside the tube to enable bending/directing the silicone tube. I'm sure with a bit more time/creativity you could get more of the 1.5 L quoted volume out. Getting to the fill port plug out was a bit more of a pain than expected because of some braces and vibration dampers in the way, but nothing too difficult to remove.

The rear diff fluid was noticeably more discolored and burnt smelling than the front diff fluid on my xDrive at ~50k miles, so I'm planning to change it more frequently. (Also because it's not a complete drain.)

This is good info. I changed the rear diff fluid in my car a couple months ago using similar advice from others on here. Bmw did away with the drain plugs in the diffs when they started calling everything 'lifetime fluids'. Whether you agree with them on this point or not is a separate discussion. Doesn't need a drain plug if you don't regularly change the fluid is their stance, I guess, So you just extract the old with a hand pump and refill through the one 'fill plug' opening. The car needs to be level to get the proper fluid quantity when refilling, so front and rear jack stands or a lift are required. It can be a bit messy so have some rags or shop towels handy.

[pw0n]

Originally Posted by andino

Temps still go up very slowly once you hit the min temp. I was able to get all the fluid in before it got any hotter than the min temp.

Tips for the pump are to make sure your car is high enough in the air to comfortably swap bottles if you want to stay under the car. I'd recommend a friend help you swap the bottles out though as I did it by myself and got covered in that smelly fluid!

Also try and angle the tip that goes into the pan slightly downward and towards the back of the pan otherwise you'll get fluid reflecting off the top of the trans and ends up on the floor (or in my case, on my shirt lmao).

Finally got around to doing this, but I'm missing something so hoping you or someone else can fill in the gap.

I've read/watched both FCP Euro's directions (https://blog.fcpeuro.com/how-to-serv...p-transmission) and ISTA+ service function for Transmission control unit: Oil-level adjustment, and the two seem to differ rather drastically (after draining and installing new transmission fluid pan).

FCP Euro's guide states to
1) perform 1st fill
2) start engine and go through ALL 8 gears
3) check temps are 30-40 C
4) perform 2nd fill

while the service function states to
1) perform 1st fill
2) start engine
3) immediately perform 2nd fill (this differs from FCP Euro's guide)
4) only shift between gears 1 and 2, and then switch to P and maintain 2k RPM for 30s (again, this is completely different from FCP's guide)

I decided to stay "safe" and follow the service function; however, when I removed the fill plug for the last time, an excessive amount of tranny fluid gushed out - took about 6-7 minutes before it started dribbling. I'm wondering if it's because I didn't go through all 8 gears?

And unfortunately, the tranny fluid quickly jumped up to 41 C, so I was unable to proceed w/ the service function, but based off a video I watched, seems like it basically ends w/ letting excess fluid out.

That said, which guide should I follow? FCP, service function, or a combination of both? And if a combination of both, what are the overlapping steps?

[pw0n]

Originally Posted by pw0n

Finally got around to doing this, but I'm missing something so hoping you or someone else can fill in the gap.

I've read/watched both FCP Euro's directions (https://blog.fcpeuro.com/how-to-serv...p-transmission) and ISTA+ service function for Transmission control unit: Oil-level adjustment, and the two seem to differ rather drastically (after draining and installing new transmission fluid pan).

FCP Euro's guide states to
1) perform 1st fill
2) start engine and go through ALL 8 gears
3) check temps are 30-40 C
4) perform 2nd fill

while the service function states to
1) perform 1st fill
2) start engine
3) immediately perform 2nd fill (this differs from FCP Euro's guide)
4) only shift between gears 1 and 2, and then switch to P and maintain 2k RPM for 30s (again, this is completely different from FCP's guide)

I decided to stay "safe" and follow the service function; however, when I removed the fill plug for the last time, an excessive amount of tranny fluid gushed out - took about 6-7 minutes before it started dribbling. I'm wondering if it's because I didn't go through all 8 gears?

And unfortunately, the tranny fluid quickly jumped up to 41 C, so I was unable to proceed w/ the service function, but based off a video I watched, seems like it basically ends w/ letting excess fluid out.

That said, which guide should I follow? FCP, service function, or a combination of both? And if a combination of both, what are the overlapping steps?

Now that I think about it, I'm definitely missing something here. FCP's guide really doesn't make any sense unless you're on a dyno (or driving). How can your car be on the ground while going through all 8 gears @ 2k?

The service function makes more *logical* sense (at least to me), but it's worrisome that it's not hitting all 8 gears from what I can tell. What am I missing here?

[andino]

Originally Posted by pw0n

Now that I think about it, I'm definitely missing something here. FCP's guide really doesn't make any sense unless you're on a dyno (or driving). How can your car be on the ground while going through all 8 gears @ 2k?

The service function makes more *logical* sense (at least to me), but it's worrisome that it's not hitting all 8 gears from what I can tell. What am I missing here?

I used the fcpeuro guide is a general guide and ultimately followed the ista service function because I wasn't able to get the car to shift beyond 2 in my service. I didn't have any fluid come out on my initial pull after filling the torque converter. I was able to add an additional 1 or 1.5L to my pan before it started dribbling out.

[pw0n]

Originally Posted by andino

I used the fcpeuro guide is a general guide and ultimately followed the ista service function because I wasn't able to get the car to shift beyond 2 in my service. I didn't have any fluid come out on my initial pull after filling the torque converter. I was able to add an additional 1 or 1.5L to my pan before it started dribbling out.

Thanks for confirming.

Okay, that's a bit concerning considering that's sorta what I tried late last night and still ran into the same issue. Perhaps the temps are what's throwing everything off - I'll try again today.

[andino]

Originally Posted by pw0n

Thanks for confirming.

Okay, that's a bit concerning considering that's sorta what I tried late last night and still ran into the same issue. Perhaps the temps are what's throwing everything off - I'll try again today.

I think it pretty variable because I was only able to get about 4L in on my initial fill before fluid started coming out. How much fluid were you able to put into the sump before going through the whole gear dance and converter filling?

[pw0n]

Originally Posted by andino

I think it pretty variable because I was only able to get about 4L in on my initial fill before fluid started coming out. How much fluid were you able to put into the sump before going through the whole gear dance and converter filling?

About 4L as well on my first fill.

And I recall you saying it takes awhile for the transmission fluid to get up to temp, but mine reached 41C while I was doing the whole gear dance (probably under 10min). It's about 75 F where I am, so I found that a bit surprising, but I think I know what's causing the rapid temp increase - I had to undo the downpipe-to-midpipe clamp to move the exhaust (I stripped the fill plug and needed more clearance to get it off, anyways...) which caused all that heat to dissipate near the transmission fluid pan instead of out through the back. I've reconnected the clamp so hoping that'll resolve my issue - will confirm when I get around to it.

[andino]

Originally Posted by pw0n

About 4L as well on my first fill.

And I recall you saying it takes awhile for the transmission fluid to get up to temp, but mine reached 41C while I was doing the whole gear dance (probably under 10min). It's about 75 F where I am, so I found that a bit surprising, but I think I know what's causing the rapid temp increase - I had to undo the downpipe-to-midpipe clamp to move the exhaust (I stripped the fill plug and needed more clearance to get it off, anyways...) which caused all that heat to dissipate near the transmission fluid pan instead of out through the back. I've reconnected the clamp so hoping that'll resolve my issue - will confirm when I get around to it.

Yeah I recall it took longer than the ista instructions suggested to get to the minimum temp for the fluid in both stages. I started the work with a totally cold car though (cooled overnight) and the instructions mentioned that it could take longer for temp to be reached if that were the case.

[F32Fleet]

Originally Posted by pw0n

Now that I think about it, I'm definitely missing something here. FCP's guide really doesn't make any sense unless you're on a dyno (or driving). How can your car be on the ground while going through all 8 gears @ 2k?

The service function makes more *logical* sense (at least to me), but it's worrisome that it's not hitting all 8 gears from what I can tell. What am I missing here?

You don't go through each gear at 2k rpms.

Run though the gears place the transmission in park and then rev to 2k rpm. The gear dance should take all of 3 min

See questions in the FCP DIY on the ZF8HP fluid change.

[eugene89us]

Here is the info directly from ZF:

Let the engine run at idling speed and then select positions R and D one after the other. Afterwards, shift gears according to the table below, depending on the transmission variant (A, B or C).

Transmission variant /Gears to be selected /Hold gear for /Additional operations
A/ 1st to 3rd/ 3 sec./ -
B/ 1st to 4th/ 10 sec./ -
C/ all/ 10 sec./ Keep the engine speed at 2,000 rpm for 30 seconds to fill the torque converter with oil.