I have a 1998 Ford Taurus and have been having trouble with my brakes. Twice now I've gone to drive it and the brake pedal easily goes to the floor and can only slow the car to a stop without having even used the gas. Upon inspection the brake fluid container was empty.

I've taken it to the mechanic twice now. The first time they replaced quite a few parts including the brake lines (I can look up the specifics on the receipt if that would help) saying that they had rusted causing the low brake fluid. The car worked well for about two months (I drive it about once a week) after which the brake light would come on intermittently after letting off the brake and sometimes during acceleration. After a few weeks of this, though, I found the brakes were gone again.

The second time I took the car in to the same place, I had filled the brake fluid first, and after they inspected it they couldn't find a problem. The brakes seemed fine after, but again about two months later the problems came back.

So, I have a few questions: * Is there any commonly overlooked problem that would cause a brake fluid leak that they could have missed twice now? Is improper installation of brake lines a possibility?
* The loss of brake function seemed somewhat sudden. They either worked fine, or could barely stop the car when I started it up. Is this normal for leaking brake fluid or possibly something else? * The mechanics said they didn't touch the brakes the second time I took the car in. Could my adding brake fluid first have resolved the problem? How long does it take for brake fluid to help, as the first time I added it it didn't seem to fix the problem after waiting a few minutes? And if adding brake fluid could have resolved the problem, would the car be safe to drive a short distance after filling the brake fluid?

Sorry for the long post, I'm just not sure if I can trust my car or the mechanics looking at it, and not knowing much about cars myself it would be great to hear some more expert opinions on the matter.

Thanks!