so i have had this same problem, 2 cars in two days. there is a silicone based brake fluid on the market that claims its "comparable to DOT3 and DOT4". HOWEVER...this fluid you sould absolutely not put in the master cylinder if it calls for dot3 or 4 brake fluid. yesterday and today i have had two cars, bot with under 30k miles come into my dealership with faulty master cylinders. i checked the fluid in both and it felt like ky jelly lol. getting no pressure from master cylinders whatsoever...this brake fluid is causing the seals in the master cylinder to stick and/or fail so BEWARE, DO NOT USE IT EVEN THOUGH ITS CHEAPER!!!! now the customers are having to pay 500 dollars a piece for master cylinder replacement. has anyone else had any experiences like this????