Hello quattrotdi!
Thank you for the information. However, I sold the A6 with the oil leak problem 2 weeks ago because I simply didn't want to deal with it anymore

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I'm going to change the signature right away

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'However, I had already replaced the refrigerant dryer (accumulator), as the internal pressure was around 10 mBar. After that, it improved somewhat. But the valve on the filter housing was definitely okay! It wasn't burning any oil either! And I didn't have any warranty on this vehicle for the refrigerant system!'
The topic, however, was actually just a side issue to the original topic we were discussing! Originally, it was about my father's car experiencing rough running, excessive smoke, and a lack of power. Fortunately, that issue has been resolved for a few months now, and it was fixed after replacing the camshafts, rocker arms, and hydraulic lifters.
Regards,
DENNIS