The brake fluid compatibility standard, S5.1.10, of 49CFR571.116 exempts DOT5 from the requirement not to stratify.
"(2) Fluids, except DOT 5 SBBF, shall show no stratification."
Further the manufacturers themselves discouraging mixing.
eg
https://www.penriteoil.com.au/assets/pdf/tech/Nov2015/Brake_Fluids.pdfAnyone switching should flush the glycol based fluids out thoroughly. Good paper referencing SAE papers and standards as well as the usually suspects from Carol Smith to various manufacturers and retailers.
http://www.niagarabritishcarclub.org/index_htm_files/Brake%20Fluid.pdfI stand by what I wrote before. Its a case by case personal decision. I personally wouldn't use SBBF in my car as I want everything in my favor on road course type use. For someone with a restored car with all new or cleaned hydraulics, its a rational choice. For road racing, of course there may not be a choice - follow the rules of the sanctioning body and host track.
