I just had this issue as well. If you do a google seach for "Mechatronic sealing sleeve" there are tons of threads about this including at BMW / ZF service bulletin. Apparently BMW nor ZF are capable of producing quality. (for search purposes AKA as "valve body" or "valve bodies")

Mine has 52k on it, was parked during thanksgiving week came out to a 4 inch in diameter puddle of fluid on the ground. Brownish tint but fairly clear, no noticable odor. Took it in today they replace the sleeve and noticed the oil filter housing had some seepage as well.

Warranty work I signed off on was $561 covered under a $50 deductible. All in all the I'm very pleased by the dealerships service, I'm skeptical about owning a BMW w/o a warranty though. Seals should not fail in 4 years or 52k, especially to the magnitude of what BMW and ZF have experienced. It appears that EVERY model that uses a ZF transmission has this problem. That's a manufacturing DEFECT and should be covered regardless of warranty up to a certain threshold of time/mileage. The only fluid my 9 year old Nissan dropped was when I did a lousy job dropping the oil filter and did a lazy job cleaning up the suspension cross member where it would pool.

Steps off soap box!!!

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'08 E70 3.0
'98 E36 M3 Convertible