Thank you very much for your extended post and valuable informations.

Oil
Denso ND-OIL8 (part no. 9990101) can be found at RockAuto: https://www.rockauto.com/en/parts/de...erant+oil,6928

Find the a/c specialist with the super-expensive a/c service station
The common problem: in the event of an A/C failure the dealers claim that they have to change the complete system (more profit, less risk). So flushing is not very common (no incentive either). The smaller shops I usually go to (one man shows) are very competent and are willing to work with you on a solution but they can't justify a super-expensive flush station. A/C spectialists with such a machine are hard to find and expect you to hand over the keys and pay whatever they want. So it's better DIY.

Flushing agent
Thanks for the hint. RockAuto does carry 4Seasons but not in stock. I'd prefer a non-flammable liquid over SuperCool.
https://www.rockauto.com/de/tools/he...em+flush,13621

Two pipes located in front of the radiator
They still look fine. Not much highway driving.
I've had no problem with the fitting or corroded aluminium 8 years ago, so it should be ok.

Suction/recharge hose
At their price tag on RockAuto I'm giving them a try.
Thanks for the hint on the fitting flange.

EPT foam
The foam attracts bacteria. Not sure if I'm going to replace it with the same type of material. That will be puzzle task whenever I see what and how is seals.

Two more questions
- How many quarts of flush agent are needed? I intend to flush each part three times, condenser many more. 2 quarts sufficient?
- How long have the components to be dried? I'm using nitrogen 2.8 but for how long?

Thanks very much again.

Now, have to order and wait for parts...