hi swede, heck and grey- i suspect there is no significance to the different colors. didnt know until today there was a red brake fluid, unless one fouled up (and this would be a real fubar) and put atf in the master. actually a pal back in the 70s put power steering fluid in his master in a 59 ford, which boiled , expanded and locked up his brakes. spent a saturday flushing his lines with clear brake fluid and had to refill and rebleed the master and 4 wheel cylinders. took over a quart of fresh fluid. of course the bleeder on one cylinder rounded and broke, so we had to replace the cylinder. can you imagine one being so po that he used power steering fluid in the brakes. so if any sage knows why brake fluid comes in at least 4 different colors , please spill your guts. get a load of this- a fellow traveler who has all his car work done on his late model fwd volvo at the dealership(that must be why he told me he was po) said oe volvo brake fluid is purple. how can you be po if you have a late model volvo. thanks tons oldduke