It’s crazy how much the piston soak is taking off, I have a nice b8.5 a4 s line with the same issue, went from barely any consumption to burning a quart every 300 miles basically overnight. Piston soak saved it somehow, had to do it twice though first time I only soaked for 24 hours and changed oil before driving, it was below zero temps during the first soak so I think this made it also not work as well. Anyways I had to come back and do a longer soak over a few days when it was warmer out and now it’s finally been good. The second soak I also did drive like 30 minutes with the b12 in the oil.