[rostrata]

Hey all. Wondering if anyone has had any experience doing their own transmission fluid changes to tell me what to expect and if there were any special circumstances around accessing the fill plug. Any special tools required? Tranny fluid changes, IME, are relatively straight forward. But I haven’t been under this thing yet to that extent and I only have a limited amount of time to mess with it when my helper shows up. Greatly appreciate any info.

[rostrata]

So! I know there were no comments or questions from others. Regardless, I was able to complete the job over the weekend and I will tell you this. It is stupid simple. However, I’d like to save you some time and money.

Take a large 8mm allen key and cut about 1/2” off the short side. You will now have a properly sized tool to get to the transmission fill plug. I went and ordered that set of compact allen sockets ($165 for four of them!) thinking they would do the trick. Nope! Even those were too damn big. Don’t waste your money. And don’t bother with them for the differentials either. Won’t fit on the front. The rear one is open and easily accessible. And the part number and place ordered from for those low profile hex keys is: http://www.ecstuning.com/b-aga-tools...-ss-8-14-k~ag/
Well machined stuff and I’m sure they’d be useful eventually. Just not for out application.

Anyway… back to the transmission pan. There is a video floating around and that will get you 90% of the way there. But that’s on an X3. So when he says there’s tons of room, that’s absolutely not applicable to the M340iX. Not sure about the rear drive only.

The torque specs for the bolts are 7.4 ft lbs. a digital torque wrench will go a long way and very important for that step.

Lastly, I used a Foxwell 530 to monitor the transmission oil temps and such. Didn’t really need to follow the steps but the temp info is good to have.

When draining and refilling, we got about 4 1/2 quarts out of it and put about 4 1/2 back. Intend to do a simple fluid exchange in a few thousand miles again to get about 75% of the fluid swapped.

For reference, I used the standard ZF8 Pentosin fluid that’s recommended for these.

Final results… fluid change was completed at around 46k miles. Shifts are back to factory new quality. Shift points don’t hang like they were. Everything just feels smoother and faster. Quite impressed. One thing to note is that my fluid came out pretty clear. It wasn’t sludgy or dark or contaminated. That was nice to see. So it just means the fluid had broken down enough over 46k miles to warrant replacement. If you drive hard, I’m betting the same is the case for yours.

Onto the Diffs. Those were disgusting. Glad I got that crap flushed out now. Should really be done around 30k given what I saw.

Very last little tidbit. The dealer quoted me $1,200 for the transmission fluid and pan replacement and $400 per differential. That’s $2k. Hell no! Go buy tools and fluid and materials and do the shit yourself. Too easy. But mind the front diff fill plug. That’s a bit of a bitch to put back once you get it off. Just be patient.

Hope these notes and anecdotes helps someone out.

[G30M]

thanks man

[AM340iMiami]

Thanks! Some pics and vids would have been nice. Next time maybe?

[rostrata]

Yeah I thought about it but was too focused on the task. Figured with the one video already available on the X3, adding some commentary would help folks out the most. That video is actually really great. Can’t really beat it.

Here’s the link to it:

[Nembus]

Originally Posted by rostrata

So! I know there were no comments or questions from others. Regardless, I was able to complete the job over the weekend and I will tell you this. It is stupid simple. However, I’d like to save you some time and money.

Take a large 8mm allen key and cut about 1/2” off the short side. You will now have a properly sized tool to get to the transmission fill plug. I went and ordered that set of compact allen sockets ($165 for four of them!) thinking they would do the trick. Nope! Even those were too damn big. Don’t waste your money. And don’t bother with them for the differentials either. Won’t fit on the front. The rear one is open and easily accessible. And the part number and place ordered from for those low profile hex keys is: http://www.ecstuning.com/b-aga-tools...-ss-8-14-k~ag/
Well machined stuff and I’m sure they’d be useful eventually. Just not for out application.

Anyway… back to the transmission pan. There is a video floating around and that will get you 90% of the way there. But that’s on an X3. So when he says there’s tons of room, that’s absolutely not applicable to the M340iX. Not sure about the rear drive only.

The torque specs for the bolts are 7.4 ft lbs. a digital torque wrench will go a long way and very important for that step.

Lastly, I used a Foxwell 530 to monitor the transmission oil temps and such. Didn’t really need to follow the steps but the temp info is good to have.

When draining and refilling, we got about 4 1/2 quarts out of it and put about 4 1/2 back. Intend to do a simple fluid exchange in a few thousand miles again to get about 75% of the fluid swapped.

For reference, I used the standard ZF8 Pentosin fluid that’s recommended for these.

Final results… fluid change was completed at around 46k miles. Shifts are back to factory new quality. Shift points don’t hang like they were. Everything just feels smoother and faster. Quite impressed. One thing to note is that my fluid came out pretty clear. It wasn’t sludgy or dark or contaminated. That was nice to see. So it just means the fluid had broken down enough over 46k miles to warrant replacement. If you drive hard, I’m betting the same is the case for yours.

Onto the Diffs. Those were disgusting. Glad I got that crap flushed out now. Should really be done around 30k given what I saw.

Very last little tidbit. The dealer quoted me $1,200 for the transmission fluid and pan replacement and $400 per differential. That’s $2k. Hell no! Go buy tools and fluid and materials and do the shit yourself. Too easy. But mind the front diff fill plug. That’s a bit of a bitch to put back once you get it off. Just be patient.

Hope these notes and anecdotes helps someone out.

Is the diff fluid the same as the transmission fluid? And I'm guessing it's 2 diffs for the x-drive right?

[rostrata]

Originally Posted by Nembus

Is the diff fluid the same as the transmission fluid? And I'm guessing it's 2 diffs for the x-drive right?

No. Definitely not the same. There are also friction modifiers that will cause serious problems for your trans, including the fact that diff fluid is super thick and would just not work in a transmission.

Recommend you use the weight specified for the diffs on this car. Pay attention to whether you have the M Sport LSD or not. That will certainly affect which fluid you use or if you need two different fluids.

GL-5 75-90 is what I used from Redline in both diffs. I read the spec sheet and using GL-4 as well made zero sense. That was a personal call though. You need to consider whether that’s correct for your application or not.

Transmission fluid I used was Pentosin ATF-8.

Hope that helps.

[Nembus]

Originally Posted by rostrata

No. Definitely not the same. There are also friction modifiers that will cause serious problems for your trans, including the fact that diff fluid is super thick and would just not work in a transmission.

Recommend you use the weight specified for the diffs on this car. Pay attention to whether you have the M Sport LSD or not. That will certainly affect which fluid you use or if you need two different fluids.

GL-5 75-90 is what I used from Redline in both diffs. I read the spec sheet and using GL-4 as well made zero sense. That was a personal call though. You need to consider whether that’s correct for your application or not.

Transmission fluid I used was Pentosin ATF-8.

Hope that helps.

Diffs been good since? BMW charges a ton for their diff fluid lol

[rostrata]

Originally Posted by Nembus

Diffs been good since? BMW charges a ton for their diff fluid lol

Oh dude. Everything is smooth as hell. Diffs love the fluid I used too. Did the diffs, transmission and engine oil all in one go. Drives better than when I got it with 3,200 miles on the clock.

[Nembus]

Originally Posted by rostrata

No. Definitely not the same. There are also friction modifiers that will cause serious problems for your trans, including the fact that diff fluid is super thick and would just not work in a transmission.

Recommend you use the weight specified for the diffs on this car. Pay attention to whether you have the M Sport LSD or not. That will certainly affect which fluid you use or if you need two different fluids.

GL-5 75-90 is what I used from Redline in both diffs. I read the spec sheet and using GL-4 as well made zero sense. That was a personal call though. You need to consider whether that’s correct for your application or not.

Transmission fluid I used was Pentosin ATF-8.

Hope that helps.

Out of curiosity, does your car have the M sport diff? I did so much researching and my only options for diff fluid aside from OEM is to use Redline for the front and a Motul molygear 75W80 that's GL5 for the rear cause I have an m-sport diff.

[rostrata]

Originally Posted by Nembus

Out of curiosity, does your car have the M sport diff? I did so much researching and my only options for diff fluid aside from OEM is to use Redline for the front and a Motul molygear 75W80 that's GL5 for the rear cause I have an m-sport diff.

Yes. I have the M-Sport diff. So our cars are identical in that respect. You CAN use the same GL-5 on the front. Those friction modifiers are simply added to allow the LSD to work properly. As I said before, you’ll have to make that choice for yourself if you want to deviate. But I couldn’t find a single piece of evidence that said it would be unwise to do so. I take that as a green light. But your car, your decision.

[cyam]

Curious. With the transmission drain/ fill, do you need to replace the pan??
Can you not simply drain from the drain plug, put the plug back in and fill from the fill plug? Is there a way to test 100% the transmission fluid level is right rather than just putting in the same amount that drained out?

[Nembus]

Originally Posted by cyam

Curious. With the transmission drain/ fill, do you need to replace the pan??
Can you not simply drain from the drain plug, put the plug back in and fill from the fill plug? Is there a way to test 100% the transmission fluid level is right rather than just putting in the same amount that drained out?

You fill it by pumping trans fluid until it starts spilling out from the fill hole then you close it up, turn the car on and warm up the trans until it gets to 50c then fill again.

[rostrata]

Originally Posted by Nembus

You fill it by pumping trans fluid until it starts spilling out from the fill hole then you close it up, turn the car on and warm up the trans until it gets to 50c then fill again.

Exactly right. You can even track the transmission temps using diags from certain OBD tools like Foxwell. Some even have step by step instructions so you can’t fuck it up.

However, to get most of the fluid out, dropping the pan is really the only way. You definitely won’t get much fluid out if you just pop the plug.

[TanzaniteM340i]

Quick couple of questions-

1. What was the exact part number/SKU for the pan/fluid you used?
2. My car is also an M340i xDrive- was the LSD optional or standard on this model? I don't know where to find that info for my car
3. For the differential fluid, what is the capacity for each diff?
4. Did you also fill the transfer case?

[Nembus]

Originally Posted by TanzaniteM340i

Quick couple of questions-

1. What was the exact part number/SKU for the pan/fluid you used?
2. My car is also an M340i xDrive- was the LSD optional or standard on this model? I don't know where to find that info for my car
3. For the differential fluid, what is the capacity for each diff?
4. Did you also fill the transfer case?

1. BMW GA8HP45Z GA8HP70Z Oil Pan and Filter Kit ZFS-1090298043
2. No, LSD is standard as far as I know but there are two types, normal and M-sport, you can find out which by putting your vin at a BMW vin decoder to see if it was spec'd that way
3. I believe each diff is around 0.9L roughly.
4. I'm not changing my TC fluid, heard that fluid is very picky so maybe another time idk

[rostrata]

Here’s the part number I have from my order through Rock Auto.

BECK/ARNLEY 0440409 (044-0409) Filter $ 112.79 $ 0.00 1

I didn’t do my transfer case either but I do plan on tackling that during my next transmission fluid change at 70k.

[aleph-one]

I have two quarts of Redline GL-5 75-85 for both diffs and one quart of MT-LV GL-4 for the tcase, which I got to put in my old X3 M40 before trading it in for an M340ix. I was just going to use this setup for the 3er because Redline likewise suggests GL-5 75-85 for both front/rear diffs on a '20 M340ix, and only recommends GL-4 for the tcase. Any particular reason you decided to go for 75-90 over 75-85 for the diffs?

Also, you mentioned the capacity for the diffs is about 0.9L, so I assume 1qt of diff fluid was enough for each diff, yeah?

Will report back on my experience with the tcase so we can keep building this M340 drivetrain megathread