Note: the FAQ thread lists the old rules as well as the Skyteam rules.
http://www.flyertalk.com/forum/9128234-post49.html

What I'm really asking is, does anyone know whether you can use a series 4 upgrade (North America to Asia) on a NW M fare? I agree I should call, but as noted in the FAQ, the agents aren't always 100% informed about this program and I'd like to know if anyone else has tried it before calling.