<e36> oil in coolant reservoir

["Georg Taht" <tfam@xxxxxxxxxxx>]

we are talking about a 1997 328i...mileage about 40K...perfect
maintenance...
it all started a coupla wks ago when
i noticed the temp gauge was wandering a bit...a little this a-way, a little
that-a-way...
then!
opened the coolant reservoir and ta-da!
oil was present in the coolant.  not good.
anyone have this experience??
so far the BMW store is telling me it's nothing...i need a new thermostat.
and oh, they ran a leakdown check, which--in my opinion--would show nothing
about what i suspect the problem really is:
a leak between the water jacket and an oil passage
or ?

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