It is the Jeep disc brake pads that will eventually wear out as the braking system on your vehicle is being used. The material they are made from is strong enough to last for quite some time, but soft enough not to damage the rotors on your Jeep. The best indication that the wear on the Jeep disc brake pads is becoming excessive and they should be replaced is when the brake fluid level in the brake master cylinder is getting low. The brake fluid is not leaking out of the system; it is just being moved to fill in the space in the brake caliper as the piston moves out further to compensate for the wear on the disc brake pads. If the brake fluid reservoir is filled before a brake job is initiated on your Jeep, when the piston in the caliper is pushed back in, the brake fluid will overflow from the reservoir and will need to be cleaned up. Another indication that the disc brake pads are worn out and in need of being replaced is when a metal to metal noise is coming from the front wheels when the braking system is being used. This is the contact of the backing plate the disc brake pads are mounted too coming in contact with the brake disc rotors. When this is heard, damaging is occurring to the brake disc rotor with grooves being cut into them. The driver will also notice the braking process is not as efficient as before and the possibility of the disc warping due to excessive heat is a possibility. If either of these conditions is noticed the replacement of the disc brake pads is necessary so your Jeep will have the ability to stop when the driver needs it too.