Originally Posted by themicah
I thought it was just T and K that were excluded. Or is that only for base members using WP miles and not OP miles?
From nwa.com for WP mile usage (so yes you are correct...I was confusing CO Q fare)
Eligibility
Non-Elite WorldPerks members may no longer use miles to upgrade to First Class on domestic itineraries when purchasing Northwest T and K type fares or Continental V, Q, T, S and L type fares.