Originally Posted by
xliioper
Unlike AA, only very expensive full J fares earn 200% MQM's on DL (DL no longer uses F class for domestic FC -- J is used for both international D1 and domestic FC). I believe all the upgrade offers book into one of the discount FC fare classes (C/D/I/Z) which earn 150% MQM's. So, yes, you will get a bonus. But it will only be 50%.
Agree in general, but note that the fare class is changed only if you purchase the upgrade in advance. At OLCI or on the day of departure, you're just paying a fee for a FC seat, without the ticket being reissued.