As an add-on comment for this thread-- the Skyteam upgrade program is truly FULL fare Y class. I recently booked a Y fare international ticket with DL and after 20 min on hold with the NW Platinum line, they told me I could not use Woldperks miles to upgrade the DL ticket because it was an international Y fare that was not classfied as "FULL Y" fare.

That points out part of the joke of this program-- the domestic segments on DL were already upgraded at time of ticketing because it was a "Y" fare but yet I could not use NW miles to upgrade the international segments under the Skyteam program because the ticket was not FULL Y.

Since DL upgrades Y/B/M tickets under its Skymiles progam, I could use miles I have on that account to upgrade my Y fare, ut but then I don't want to lose the NW miles collection and EQM collection when others tell me I will lose that benefit if I pay the miles with DL.

So at the end of the day, my million plus NW miles are still worthless, because I cannot use them to upgrade a Y ticket and don't want to risk losing the EQM by using DL Skymiles for the upgrade since I am told I will then earn Skymiles EQM instead.