Thank you for your replys.
Still no answer from Chrysler.
Castrol Technician phoned me. He advised that Castrol Edge was the recommended product from the Castrol range.
I contacted dealership service division. Service manager said he would need to speak with the Castrol rep for them. Service manager got back with advice that product the Castrol rep recommended was Castrol TXT Softec as used by the dealership on VW services and in the CHRYSLER 300C HEMI. Service manager said I could book Coupe in for service to change to Castrol TXT Softec. He did not know what oil was in the Coupe now, Magnatec or Softec as they had both in stock and which one used was not on my vehicles service record.
I am not aware of Castrol TXT Softec so I will check again with Castrol on Monday.
For interest I will follow this through.
Looks like I will go to the Mobil 1 Signature Centre from here on.