when does timing belt need to be changed

Short answer: before it snaps and turns your engine into modern art. Most cars with a timing belt want it replaced every 90,000–150,000 km or 5–10 years, whichever comes first. If you tow, do short trips, or live with heat, dust and stop‑start traffic, aim for the earlier end. Many newer cars use a timing chain instead—no scheduled replacement, but they still need clean oil and can wear. A failed belt on an interference engine can bend valves and empty your wallet faster than a pokie machine, so don’t push it. Check your owner’s manual and service schedule for your exact interval, or ask a trusted mechanic; consult official documentation for exact figures.