I'm the second owner of the X5. It's a 2008 with 252k on the clock. I'm chasing down a shudder issue I'm experiencing only after the car is warmed up after bout 20 minutes of driving and typically only manifests itself in stop and go traffic. Primarily the issue is when the car shifts from 1 to 2 this is followed by a shudder / loss of power. If I press the gas more the transmission kicks down and it accelerated without issue. Also, I can't typically eliminate the issue by switching the car into sport mode.

The transmission fluid has never been changed because I was told not to at around 125k by local shops and the dealer. They said flat out don't do it because the friction material would be lost and the transmission will slip. So, I didn't.

It's been great until recently where this shudder is becoming annoying. It's not horrible, but I would like it gone.

Now this could be fuel system, coils, spark plugs, vanos, injectors or valvetronic motor, eccentric shaft sensor, or torque converter or transmission related.

I've already ruled out vanos, check valves, spark plugs and coils. I've tested end stops on the valvetronic motor and it seems to be working. I'll be testing the injectors and fuel pump today.

My next course of action is as follows.
1. Replace the valvetronic motor because it could be failing as it heats up and degrades in performance. Others have seen this and it's very difficult to diagnose but it results in the same issue as I'm having.
2. Add Lubegard Instant Shudder Fixx to the transmission.
3. Drain and change the transmission fluid and filter and while in there inspect the seals and other parts replacing if needed.
4. Do everything in step 3 but also add Lubegard Instant Shudder Fixx.

Does anyone have any experience with this and could offer some insight / advice?

Thanks in advance!

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2008 X5 3.0si
256k Strong