A timing belt can sometimes last 10 years, especially on a low-mileage vehicle, but that does not mean it should be trusted. Timing belts are made with reinforced rubber, and rubber ages even when the vehicle is not driven much. Heat, moisture, oil leaks, coolant leaks, and prolonged sitting can all weaken the belt. Some manufacturers list a time interval as well as a mileage interval, while others focus mainly on mileage. If your belt is near 10 years old, check the maintenance schedule and service history, then plan replacement unless the manufacturer clearly allows more time. Age-related failure can happen suddenly and may lead to expensive engine damage on many vehicles today, without warning.