The outside is designed to take some abuse. If the outside sheath shows quite a bit of abuse or any of the inner core is showing, it is time to replace the rope. It should also be replaced if the rope has been subjected to a major fall. A major fall exerts tremendous forces on the rope and does considerable damage to the core. Don't use a rope that is over 5 years old.
Time wears down the rope's strength and ability to stretch.
Also, never exposure your rope to chemicals, especially battery acid, which might be stored in your car trunk next to your climbing gear. There's a case where a rope failed because car batter acid had weakened it. The rope had been stored near a car battery. East 3900 South Salt Lake City, UT 84124, USA Tel. Blue Water 209 Lovvorn Road Carrollton, GA 30117, USA Tel.