Squealing brakes

[T5_X]

My front brakes have been squealing for a while. Naturally, I assumed it was the pads as I hav'nt replaced them since I got my car 25,000 km ago. I took things apart today to find that the pads look almost brand new! There is less than 5% wear on them. Another wierd thing is that even with the cap off the master cyl, I pushed the caliper pistons as hard as I could but could not budge them back into thier bore.... Should'nt they slide back fairly easily? WTF is going on? Its certainly not the rear brakes squealing. What could be causing the squealing?

[DBFORDTECH]

Brake noise is often caused by vibration.
Clean the backs of the pads (non friction side) ensure there is
no rust. make sure the shims (if your pads have shims) are
still in good shape and no rust.
also clean the caliper mounting bracket, and ensure the caliper
guide pins are free to slide.
Lube the guide pins with brake lube....nothing else!
If your car uses anti rattle clips, or springs make sure they
are not missing, or broken.
You can treat the non friction side of the pad with an anti squeal
compound, or get a shim kit for it. I have also been known to
use brake lube on the NON FRICTION side of the pad after the
pad is clean.
As for pushing your caliper pistons in, you will probably need
a c-clamp to do it, most wont go in by hand.

[T5_X]

Hmmm, well I cleaned everything with aerosol cleaner. Very little rust though. The guide pins were lubed up good, they are sliding easily and freely. I might just try lubing up the non friction side of the pads.