[admranger]

I just did the F&R diffs and transfer case on my 2021 X7 40i w/just 25k miles. I concur the fluids were a hot (literally) mess. I was surprised at how dark they were (sorry, no pics). What was even more surprising was how hot the front diff was. It was too hot touch even after sitting for over 30 minutes! Explains why the fluid looked so crappy.

Madsen203 I had the same issue as you did with the transfer case. Even after activating the diff via my buddy's fancy diagnostic tool for the oil change service to allow for more fluid to be pulled out, not a lot came out. I was able to put roughly 400ml into the transfer case before it would run out. I kept waiting, trying to put a little more in but it just kept coming out. I'll do it again in a bit to try to take more of the old out, but I don't have high hopes I'll ever get a complete flush done. Not having a drain plug is silly. It's a huge PITA to get the suction tube into the crevices of the transfer case. My buddy had an air powered suction tool to I just moved it around until no more fluid came out from any spot I put the hose.

Overall I'm happy I did the change and recommend that it be done. I put magnetic plugs in the F&R diff. I only had two so I didn't do the transfer case as it was the last thing I did.

[DishoomX2]

Originally Posted by Madsen203

Finished doing the front today. Pain in the ass but mostly because I did it when the motor was still hot. Fluid was dark as I anticipated. Put fresh plugs on and buttoned it up. Likely won’t touch it again until 50k.

With monkeying around accessing full plug, getting diff oil in eye having to flush it, and cleaning up, took under an hour total.

Hi there. I appreciate the details of your experience. Did you need to place your vehicle on jackstands to get access? When I changed the engine oil, I only partially lifted the front to give me enough access. I I'm always wary about getting underneath, even when using 2 jacks and 2 jackstands. Would raising the vehicle at its highest setting and parking on some thick wood planks make it high enough without using jackstands?



Can the fluids be changed even without a software reset? Also, any thoughts on using Redline diff fluids for front/rear as opposed to the BMW branded?

[Madsen203]

Originally Posted by DishoomX2

Hi there. I appreciate the details of your experience. Did you need to place your vehicle on jackstands to get access? When I changed the engine oil, I only partially lifted the front to give me enough access. I I'm always wary about getting underneath, even when using 2 jacks and 2 jackstands. Would raising the vehicle at its highest setting and parking on some thick wood planks make it high enough without using jackstands?



Can the fluids be changed even without a software reset? Also, any thoughts on using Redline diff fluids for front/rear as opposed to the BMW branded?

I use OEM just because it’s a small amount and the factory stuff appears OK. You can change diff without software reset. I’m not convinced that you need to reset adaptions for TC as it only changed 0.1°.

I put car in highest suspension mode. Enough space to work under but not luxurious as being on stands or lift.

[admranger]

Originally Posted by Madsen203

I put car in highest suspension mode. Enough space to work under but not luxurious as being on stands or lift.

Please don't rely on the air suspension alone when working under the X7. A leak or a failure of the strut, while an extremely unlikely occurrence, would prove painful at best and damaging at worst.

The X7 has a front, center jacking point making putting the front up on jack stands a non-event if you have a decent floor jack. Just use a piece of wood between your jack and the diff to jack up the rear of the car.

[Madsen203]

Originally Posted by admranger

I just did the F&R diffs and transfer case on my 2021 X7 40i w/just 25k miles. I concur the fluids were a hot (literally) mess. I was surprised at how dark they were (sorry, no pics). What was even more surprising was how hot the front diff was. It was too hot touch even after sitting for over 30 minutes! Explains why the fluid looked so crappy.

Madsen203 I had the same issue as you did with the transfer case. Even after activating the diff via my buddy's fancy diagnostic tool for the oil change service to allow for more fluid to be pulled out, not a lot came out. I was able to put roughly 400ml into the transfer case before it would run out. I kept waiting, trying to put a little more in but it just kept coming out. I'll do it again in a bit to try to take more of the old out, but I don't have high hopes I'll ever get a complete flush done. Not having a drain plug is silly. It's a huge PITA to get the suction tube into the crevices of the transfer case. My buddy had an air powered suction tool to I just moved it around until no more fluid came out from any spot I put the hose.

Overall I'm happy I did the change and recommend that it be done. I put magnetic plugs in the F&R diff. I only had two so I didn't do the transfer case as it was the last thing I did.

I’m always afraid of the magnet breaking off and getting sucked into the gears. With heat cycles, NVH, and the like, seems risky.
The TC was a pain. I’ll keep doing small fluid exchanges every 5k with oil changes to help cycle in fresh fluid. Can’t hurt and I have plenty of the fluid left.

[Madsen203]

Originally Posted by admranger

Please don't rely on the air suspension alone when working under the X7. A leak or a failure of the strut, while an extremely unlikely occurrence, would prove painful at best and damaging at worst.

The X7 has a front, center jacking point making putting the front up on jack stands a non-event if you have a decent floor jack. Just use a piece of wood between your jack and the diff to jack up the rear of the car.

True. I thought about that several times. Especially after having witnessed a Land Rover air shock fail in a spectacular fashion at 3a while parked at the camp ground. However, his failure was related to a after market unit and a “cheat” he installed that forces it to raise higher than typical factory settings.
I thought about adding a jack. The only issue would be the TC. Accessing the front or rear diff from front/rear of car is a non issue. But the center can get to be a tight fit pretty quick!