[70sum]

I have a problem with the front brakes on my 03 Mustang. 45,000 miles. A little history. The gas mileage had made a drastic drop, so I started looking for reasons for the drop. I found the driver side front wheel hard to turn when the car was jacked up. I found the front caliper frozen and it would not release the pressure on the rotor. I replaced the caliper and brake shoes and hose and all was good for a few months. I have noticed a slight drop in gas mileage so I jacked the car up and found the wheel hard to turn again. I removed the wheel and checked the caliper. It is not frozen this time. All looks good. The rotor turns free with out the caliper on. The only thing I noticed is the brake fluid is not as clean as it is right from the bottle. It has never been replaced. Could dirty brake fluid keep the brake pads from releasing so they do not drag on the rotor?

[mustanginky]

could, but i doubt you'd need to change fluid after 45k miles especially after bleeding the brakes out after the first caliper change. wonder if your master cylinder is messed up or something.

[davidstivers09]

+1 agreed. Sounds like a master cylinder prob!

[WLJohnson05]

a bit of light reading for you
Maintaining Your Brake Fluid - Brakes | Home Improvement - Everything.com

[Gandolf]

If the caliper was stuck chances are it seriously overheated the pads, fluid, old caliper and probably the hose going to it. Usually they have to replace the fried rotor and bearings too along with the hose. Over achievers can even ruin the tire bead and steering joints. If they bleed the breaks at all when the caliper was replaced that should have flushed the fluid somewhat but it is hard to completely flush all the fluid. However, a burned hose still in the car can release burnt material back into the fluid. The big danger there is with a very hard application of the breaks a damaged hose my simply burst and fail and your breaking suddenly goes away when you need it most..

Light discoloration/contamination will not hurt anything. The worry is if it is being caused by something serious. If you bleed the breaks or replace the hose, don't let air get into the ABS unit since air in those needs a $$ dealer tool to get out. Those are the things to think about...

It would have been nice if they tore the stuck caliper open to determine what cased the problem in the first place. That obviously helps to be sure the real problem is indeed fixed.

Hope this helps.