Hoses and belts should be checked on a regular basis and replaced if they become cracked, brittle, frayed, loose or show signs of excessive wear. These are critical to the proper functioning of the electrical system, air conditioning, power steering and the cooling system. Most belts and hoses fail from the inside out. Rubber hose can deteriorate with age and exposure to heat. Today's hoses can often last 6 to 8 years without a problem, but eventually the synthetic material will become hard and brittle. Tiny cracks develop in the rubber which eventually cause the hose to split, blister or leak. When Oil has leaked onto the outside of coolant hose, the breakdown of the material is often accelerated. Oily hoses should be replaced as soon as possible.