O.P.,

- How many miles in your E53 M54 engine?
- I have not read every paragraph but did you replace the OFH Gasket yet?
- For the oil pan gasket: BMW only (no aftermarket), it is not expensive.

BTW, if the leak is minor, live with it.
- Again, I'd appreciate if you can do the BavarianE39 CCV Mod (crankcase vacuum will increase) and report back if it stops (or minimize) your presumed RMS leak. I'd love to know if increased crankcase vacuum solves the RMS leak!

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