Not sure if we have winter blends at the stations now but typically with my tune/mods I struggle on winter 93 due to the easier ignition so running 2-3 gallons of E85 sorts out the knock-retard. Here are 2 logs...1 with 93, 1 with E22 (2.5 gal of E to a 14.5 gal tank of 93). These are third gear pulls to redline. If anyone is interested....I always like looking at logs! I typically look at boost, timing advance, knock on all 4 cylinders, lamda, and intake air temp vs. ambient. 60 degree cool temps....turbo cars love it....boost season!
93:
E22:
93:
E22: