This page collects some data on performance brake fluid:
https://parsbrorc.com/?page_id=33
Looks like you can bump up to Endless RF650, Torque RT700, or Castrol SRF
Also, as others suggested, try either solid rotors with the cryo treatment or the racing brake 2pc rotors, which are thicker than Z1’s. I believe it’s 32mm vs 28mm