Hi all, first post.

I'm relatively new to the world of upgrades, especially as it relates to SA.

I'm going to be flying KBL-JNB, JNB-ODS, ODS-KBL ---- all on Turkish Airlines. I have about 90k United mileage plus miles on my account and would like to use SA to upgrade from economy to business on the TK flights. As my organization buys only unrestricted tickets, what fare code should I get in order to upgrade with my United miles ? I am currently looking at getting B class tickets, which according to the TK web site are upgradable (along with Y). My question is - is there a discernable difference in the amount of miles it takes to upgrade between Y and B classes ?