09112024, 05:01 PM  #111  
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So far, it hasn’t fallen off. Maybe I’ll replace them in the future but seems a bit overkill as I’m not racing or doing anything to stress this car. Haven’t noticed any difference or odd noises. 

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09112024, 08:00 PM  #113 
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Subscribed. If purchasing a new X7 M60 would you change all fluids after 5000 miles or 2500 miles. I have not ordered one yet. I would also check fluid levels during delivery before purchase as some have said that the fluid levels were low from mfg.

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09122024, 05:17 PM  #114  
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I wouldn’t change them but topping them off is a good idea if they are in fact low. I’m going to keep exchanging 200ml of the TC fluid each oil change I do (5k mi) given I can’t fully drain it each time. I’ll do the differentials at 25k intervals. 

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09122024, 05:19 PM  #115  
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To estimate how long it will take to replace most of the fluid through partial fluid changes, you can use a logarithmic approach to model the dilution process. Here's a breakdown of the math: ### Given:  Total fluid in the system: 700 ml  Amount replaced at each service: 200 ml  Frequency: Every 5,000 miles Each time you replace 200 ml of the 700 ml, you're leaving behind some percentage of the old fluid. The proportion of old fluid left after each replacement is: \[ \text{Proportion of old fluid remaining} = \frac{700  200}{700} = \frac{500}{700} = 0.714 \] After each replacement, 71.4% of the old fluid remains. To determine how many replacements (or miles) it takes for the fluid to become mostly fresh, you can set a threshold for what "mostly fresh" means. Let’s assume you want less than 5% of the original fluid remaining. You can calculate the number of replacements using the formula for exponential decay: \[ \text{Fraction of original fluid remaining after } n \text{ replacements} = 0.714^n \] Set this equal to 0.05 (for 5% remaining) and solve for \(n\): \[ 0.714^n = 0.05 \] Taking the logarithm of both sides: \[ n \log(0.714) = \log(0.05) \] Solve for \(n\): \[ n = \frac{\log(0.05)}{\log(0.714)} \] It will take approximately 8.9 fluid replacements for the fluid to be mostly fresh (less than 5% of the original fluid remaining). Since the replacements happen every 5,000 miles, the total distance before the fluid is mostly fresh is: \[ 8.9 \times 5,000 = 44,500 \text{ miles} \] So, after about 44,500 miles, the fluid will be mostly fresh since the factory build. 

09122024, 05:22 PM  #116 
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No one said there'd be math Madsen203.
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09122024, 05:31 PM  #117 
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This guy maths!
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09122024, 05:46 PM  #118 
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This guy leverages AI! ** FTFY
So if one would want to swap fluid, they would have to do it 9 times with a short drive between each exchange. Or figure out what black magic BMW uses to exchange fluid as they supposedly drain it entirely. I don’t think vacuum is enough to get it all out but I don’t have personal experience with this so I could be wrong. 
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09132024, 09:04 AM  #119  
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09132024, 09:23 AM  #120 
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Just a fair warning to folks going to dealer for xfer case service, it is a pita to drain and fill the case properly and follow the ista procedure. Not saying all, but a lot of techs pull out what they can, top it off and call it a day. I was on the phone with friends at the dealer and basically laughed and said, yeah we don't even bother changing the fluid.
Ultimately, they advised me to modify thin brake line bent to a 90 deg angle and ovaling out the end to slip it down deep into the case and extract while using ista to open the 2nd resoivor. Despite how much I love to DIY I went armed with this info to my trusted BMW indy and they let me in the shop to hang out. We ended pulling about 900ml out of the case. 
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09142024, 01:07 PM  #122  
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Albeit thin, didn’t fit. I’ll be trying this again tonight. 

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09142024, 03:38 PM  #123 
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I was wondering if something like that wouldn't be the hot setup. Keep us informed!
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09142024, 03:52 PM  #124  
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Also, unlike some pictures and videos I've seen, my differential has cooling fins and sensor wire plugged into it. Is this unique to M50i or DHP package? I covered it well with a plastic bag before starting the job. I have no idea what that one threaded hole is for (see pic)  is something missing? I've done several oil changes and brake jobs before, and although this should have been straight forward, I found it more difficult than I thought it would be. Perhaps I had a tough time extracting because I needed to drive around more to heat the diff oil up? I wasn't able to get to the front diff today, but don't look forward to it considering I found the rear diff to be a pain. 

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09142024, 09:06 PM  #125  
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09152024, 03:17 PM  #126 
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Change your fluid folks. I changed the front diff today. 50i has 25,960 miles. Drained approximately 500mL. So about 100mL short. I could definitely see a shimmer in the oil in the sunlight. The service manual only shows 10 bolts that hold the stiffening plate. It had 12 on my car.

09182024, 03:40 PM  #127 
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4mm OD tube
I ordered this to fit into the 6mm tube with the CTA 200ml suction hand pump I had. Perfect fit and no modifications needed. I was able to fish this much deeper than the 6mm tube and could in theory extract all the fluid. I only had 700ml of fluid leftover from when I first did this 5k miles ago so I pulled 600ml and refilled it until it dripped out. Fluid was merky brown and looked slightly dirty but could be heat which changed the fluid darker. Alas, now 80%+ of the fluid is fresh. Used ISTA service function to open reservoir and also do the adaptions reset. I plan to do this exchange once more at 40k miles (in 10k) but that time, pull all the old fluid out and start totally fresh. Took about 1 hour start to finish. I also pulled 400ml of fluid from rear differential and added in 450 (it was a hair shy on last fill after putting a full liter into it). I had the extra bottle laying around so I figured it couldn’t hurt while I was down there. All in all, worth doing it yourself if you have the flexibility and willing to get a little messy. Not a bad job once you get oriented under the car. No need to remove the TC brace either with the hose and CTA 19>17mm cap tool. Let me know if you need any other info! 
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09182024, 10:00 PM  #128  
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After changing the TC fluid today, it’s GONE! Couldn’t be happier with the results. 

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09192024, 09:31 AM  #129  
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My TC fluid was replaced last month but the jitter is still there in low speeds as well as brake pulsating. There’s also a harshness/vibration where the car doesn’t feel as smooth over bumps as it used to. Multiple people (foreman, BMW rep) drove it and feel it, but couldnt pinpoint to anything. I wonder if that’s also a related symptom. Either way made appointment and hopefully they will replace TC this time and it will fix all the issues. 

09202024, 02:10 PM  #130 
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For those attempting DIY, here is a nice writeup over on the X3m page https://x3.xbimmers.com/forums/showthread.php?t=2119690

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09202024, 03:49 PM  #131 
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hi all  in references to the issues revolving around the fluid… is one of them a kindof clunking when you turn right (clunk on right front) or left (clunk on left front)? We have a unicorn 2020 M50i with 20,500 miles so very low miles but obviously out of warranty at this point.
I haven’t seen the same issue description so far on this thread so I thought it was time to specifically ask. Thanks! John Last edited by bradythedog12; 09202024 at 03:56 PM.. 
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09202024, 04:10 PM  #132  
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Have you ever had a 4 wheel drive truck? Its the same feeling as leaving it in 4wd and turning in parking lots. 

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