As a Plat who does this route 5 or 6 times a year, I've generally always gotten the upgrade-----although never at a 5 day mark. Even with an almost empty F showing on flight days, they seem to wait until actual boarding for upgrades. Hubby is one of those non elites who "will only fly in F )... so for him I'll use miles to 'ensure' his F seat, 9 times out of 10-- I'm upgraded at the gate and find the F cabin full of day of departure upgrdes.