Where does my brake fluid go? When checking the fluids, on a weekly basis as you should be doing, you notice the brake fluid slowing dropping, with no noticeable leaks, until you decide it is time to add some. Hint: deplete the pressure in the system if you have ABS or for that matter on any vehicle built since 1990, safer to pump the pedal a few times then end up with a face full of fluid.As your brake pads wear the cylinder in the caliper moves out to take up the space from the wearing pad. Many new vehicles have large calipers and pistons and this is where your fluid is going. This is also why it is important to remove the master cylinder cover during brake replacement. Never let the fluid from the caliper return to the system when compressing the caliper this will contaminate the fluid and will cause ABS problems. Loosen the bleeder screw when compressing the cylinder and clamp off the brake hose. A set of plastic pliers is now available to block off the hose and they will not cause any hose damage. They are also self locking and cheap. Have heard of several internal brake hose failures, which are a SOB to diagnosis, I expect most of these are from improper pliers being used to block off the brake hose. Do not use a vicegrip better to go without then use them as a clamp. When I replace brakes I also exchange the fluid it is an easy time to do it and will prevent problems in the future. I have solved many ABS problems by changing the fluid. Do not let the fluid run low as you will need a scanner to reset the brake lite on many vehicles. Without the use of a scanner some of the fluid will not be replaced, on some ABS units, but unless it is in really bad shape this should not be a problem. If it is in bad shape seal the system, start and pump the brakes several times, and then run some more fluid through the system. Still bad time for a trip to a shop. Remember fluid does not run through the system it merely applies and releases pressure. This is why it is important to remove the fluid from the caliper as it is contaminated with wear from the piston seal and the outer wall of the piston the seal does not keep everything out.Remember it is a problem if your car doesn’t start but it is a huge problem when it fails to stop.