How many miles on the odometer?

- Check for combustion gas in coolant.

- I personally did the "BavarianE39 CCV mod" some 10 years ago, around 2016.
You can find details in this forum.
Never look back. Factory CCV system is very troublesome.
The CCV mod reduced my oil consumption down to almost zero.

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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT